[jira] [Commented] (FELIX-3456) Component ignores required static service addition when in Activating state
[ https://issues.apache.org/jira/browse/FELIX-3456?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13286524#comment-13286524 ] Felix Meschberger commented on FELIX-3456: -- So, I implemented something I think will work where the java.util.concurrent reentrant lock is used if available and if not doug lea's unfair lock. +1 Basically the solution to 3317 is no longer relevant and we can simplify the code a bit more. Right. Component ignores required static service addition when in Activating state --- Key: FELIX-3456 URL: https://issues.apache.org/jira/browse/FELIX-3456 Project: Felix Issue Type: Bug Components: Declarative Services (SCR) Affects Versions: scr-1.6.0 Environment: Using org.apache.felix.scr svn rev 1298268 on Mac Reporter: Richard Ellis Priority: Critical Attachments: FELIX-3456-1.1.diff, FELIX-3456-1.diff, FELIX-3456-3.diff, FELIX-3456-4.diff, FELIX-3456-5.diff, FELIX-3456-5a.diff, FELIX-3456-5b.diff, FELIX-3456-7.diff, FELIX-3456-7a.diff, FELIX-3456-fmeschbe-6.patch, FELIX-3456-fmeschbe.patch I have a component with two required static service references (A and B). In my scenario A and B are registered nearly simultaneously on different threads and this causes the DependencyManager to ignore the addition of one of these two services (B). This causes the component to remain unsatisfied and never activate, since the service that was ignored is not re-registered at any time and nothing subsequently causes the component to re-activate. This happens as follows: 12:30:59:317 Thread 1 - Registers Service B/257 12:30:59:320 Thread 2 - Registers Service A/258 12:30:59:320 Thread 2 - Dependency Manager: Adding Service A/258 12:30:59:321 Thread 2 - Dependency Manager: Service serviceA registered, activate component 12:30:59:321 Thread 2 - State transition : Unsatisfied - Activating 12:30:59:321 Thread 2 - Activating component 12:30:59:321 Thread 1 - Dependency Manager: Adding Service B/257 12:30:59:321 Thread 2 - Dependency not satisfied: serviceB 12:30:59:321 Thread 1 - Dependency Manager: Added service serviceB is ignored for static reference --- I believe we end up here because Thread 2 has moved the component from Unsatisfied to Activating and the reference is a static reference 12:30:59:321 Thread 2 - Not all dependencies satisified, cannot activate 12:30:59:321 Thread 2 - State transition : Activating - Unsatisfied Because the addition of Service B has been ignored and serviceB is a required dependency my component then never activates even though my reqiured service is present. There is a comment in DependencyManager#serviceAdded method: // FELIX-1413: if the dependency is static and the component is // satisfied (active) added services are not considered until // the component is reactivated for other reasons. This suggests that the static service should only be ignored if the component is satisfied(active), which would be correct, but in this case the component is only activating (and will fail to activate because one of the two dependencies is not yet satisfied) and there is no check of state at this time. A simple fix would be to check the state of the component as well as if the service is static e.g. replace if ( m_dependencyMetadata.isStatic() ) with if ( m_dependencyMetadata.isStatic() m_componentManager.getState() == AbstractComponentManager.STATE_ACTIVE ) This is an easy fix, but I guess may leave a small window where a static reference could get replaced while a component was still activating if another instance of the same service was registered on a different thread. There are other fixes that could be done by synchronizing more around service additions. Is anyone willing to make this fix or does anyone have any thoughts about this issue? Thanks -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Commented] (FELIX-3456) Component ignores required static service addition when in Activating state
[ https://issues.apache.org/jira/browse/FELIX-3456?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13286547#comment-13286547 ] Felix Meschberger commented on FELIX-3456: -- I have commited the final patch 7 in Rev. 1344701 Tests still pass. Please verify in your environment. Thanks. Component ignores required static service addition when in Activating state --- Key: FELIX-3456 URL: https://issues.apache.org/jira/browse/FELIX-3456 Project: Felix Issue Type: Bug Components: Declarative Services (SCR) Affects Versions: scr-1.6.0 Environment: Using org.apache.felix.scr svn rev 1298268 on Mac Reporter: Richard Ellis Priority: Critical Attachments: FELIX-3456-1.1.diff, FELIX-3456-1.diff, FELIX-3456-3.diff, FELIX-3456-4.diff, FELIX-3456-5.diff, FELIX-3456-5a.diff, FELIX-3456-5b.diff, FELIX-3456-7.diff, FELIX-3456-7a.diff, FELIX-3456-fmeschbe-6.patch, FELIX-3456-fmeschbe.patch I have a component with two required static service references (A and B). In my scenario A and B are registered nearly simultaneously on different threads and this causes the DependencyManager to ignore the addition of one of these two services (B). This causes the component to remain unsatisfied and never activate, since the service that was ignored is not re-registered at any time and nothing subsequently causes the component to re-activate. This happens as follows: 12:30:59:317 Thread 1 - Registers Service B/257 12:30:59:320 Thread 2 - Registers Service A/258 12:30:59:320 Thread 2 - Dependency Manager: Adding Service A/258 12:30:59:321 Thread 2 - Dependency Manager: Service serviceA registered, activate component 12:30:59:321 Thread 2 - State transition : Unsatisfied - Activating 12:30:59:321 Thread 2 - Activating component 12:30:59:321 Thread 1 - Dependency Manager: Adding Service B/257 12:30:59:321 Thread 2 - Dependency not satisfied: serviceB 12:30:59:321 Thread 1 - Dependency Manager: Added service serviceB is ignored for static reference --- I believe we end up here because Thread 2 has moved the component from Unsatisfied to Activating and the reference is a static reference 12:30:59:321 Thread 2 - Not all dependencies satisified, cannot activate 12:30:59:321 Thread 2 - State transition : Activating - Unsatisfied Because the addition of Service B has been ignored and serviceB is a required dependency my component then never activates even though my reqiured service is present. There is a comment in DependencyManager#serviceAdded method: // FELIX-1413: if the dependency is static and the component is // satisfied (active) added services are not considered until // the component is reactivated for other reasons. This suggests that the static service should only be ignored if the component is satisfied(active), which would be correct, but in this case the component is only activating (and will fail to activate because one of the two dependencies is not yet satisfied) and there is no check of state at this time. A simple fix would be to check the state of the component as well as if the service is static e.g. replace if ( m_dependencyMetadata.isStatic() ) with if ( m_dependencyMetadata.isStatic() m_componentManager.getState() == AbstractComponentManager.STATE_ACTIVE ) This is an easy fix, but I guess may leave a small window where a static reference could get replaced while a component was still activating if another instance of the same service was registered on a different thread. There are other fixes that could be done by synchronizing more around service additions. Is anyone willing to make this fix or does anyone have any thoughts about this issue? Thanks -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Commented] (FELIX-3456) Component ignores required static service addition when in Activating state
[ https://issues.apache.org/jira/browse/FELIX-3456?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13280664#comment-13280664 ] David Jencks commented on FELIX-3456: - oops, 7 is the full patch, 7a is a diff from your -6 patch. Component ignores required static service addition when in Activating state --- Key: FELIX-3456 URL: https://issues.apache.org/jira/browse/FELIX-3456 Project: Felix Issue Type: Bug Components: Declarative Services (SCR) Affects Versions: scr-1.6.0 Environment: Using org.apache.felix.scr svn rev 1298268 on Mac Reporter: Richard Ellis Priority: Critical Attachments: FELIX-3456-1.1.diff, FELIX-3456-1.diff, FELIX-3456-3.diff, FELIX-3456-4.diff, FELIX-3456-5.diff, FELIX-3456-5a.diff, FELIX-3456-5b.diff, FELIX-3456-7.diff, FELIX-3456-7a.diff, FELIX-3456-fmeschbe-6.patch, FELIX-3456-fmeschbe.patch I have a component with two required static service references (A and B). In my scenario A and B are registered nearly simultaneously on different threads and this causes the DependencyManager to ignore the addition of one of these two services (B). This causes the component to remain unsatisfied and never activate, since the service that was ignored is not re-registered at any time and nothing subsequently causes the component to re-activate. This happens as follows: 12:30:59:317 Thread 1 - Registers Service B/257 12:30:59:320 Thread 2 - Registers Service A/258 12:30:59:320 Thread 2 - Dependency Manager: Adding Service A/258 12:30:59:321 Thread 2 - Dependency Manager: Service serviceA registered, activate component 12:30:59:321 Thread 2 - State transition : Unsatisfied - Activating 12:30:59:321 Thread 2 - Activating component 12:30:59:321 Thread 1 - Dependency Manager: Adding Service B/257 12:30:59:321 Thread 2 - Dependency not satisfied: serviceB 12:30:59:321 Thread 1 - Dependency Manager: Added service serviceB is ignored for static reference --- I believe we end up here because Thread 2 has moved the component from Unsatisfied to Activating and the reference is a static reference 12:30:59:321 Thread 2 - Not all dependencies satisified, cannot activate 12:30:59:321 Thread 2 - State transition : Activating - Unsatisfied Because the addition of Service B has been ignored and serviceB is a required dependency my component then never activates even though my reqiured service is present. There is a comment in DependencyManager#serviceAdded method: // FELIX-1413: if the dependency is static and the component is // satisfied (active) added services are not considered until // the component is reactivated for other reasons. This suggests that the static service should only be ignored if the component is satisfied(active), which would be correct, but in this case the component is only activating (and will fail to activate because one of the two dependencies is not yet satisfied) and there is no check of state at this time. A simple fix would be to check the state of the component as well as if the service is static e.g. replace if ( m_dependencyMetadata.isStatic() ) with if ( m_dependencyMetadata.isStatic() m_componentManager.getState() == AbstractComponentManager.STATE_ACTIVE ) This is an easy fix, but I guess may leave a small window where a static reference could get replaced while a component was still activating if another instance of the same service was registered on a different thread. There are other fixes that could be done by synchronizing more around service additions. Is anyone willing to make this fix or does anyone have any thoughts about this issue? Thanks -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Commented] (FELIX-3456) Component ignores required static service addition when in Activating state
[ https://issues.apache.org/jira/browse/FELIX-3456?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13277809#comment-13277809 ] Felix Meschberger commented on FELIX-3456: -- makes the enable/activate and disable/deactivate happen per spec as enable/disable immediate and activate/deactivate asynchronous. As I said before, these are already asynchronous because the BundleComponentActivator.enableComponent and .disableComponent schedule the actual call to activateInternal and deactivateInternal for asynchronous execution. Component ignores required static service addition when in Activating state --- Key: FELIX-3456 URL: https://issues.apache.org/jira/browse/FELIX-3456 Project: Felix Issue Type: Bug Components: Declarative Services (SCR) Affects Versions: scr-1.6.0 Environment: Using org.apache.felix.scr svn rev 1298268 on Mac Reporter: Richard Ellis Priority: Critical Attachments: FELIX-3456-1.1.diff, FELIX-3456-1.diff, FELIX-3456-3.diff, FELIX-3456-4.diff, FELIX-3456-5.diff, FELIX-3456-5a.diff, FELIX-3456-5b.diff, FELIX-3456-fmeschbe.patch I have a component with two required static service references (A and B). In my scenario A and B are registered nearly simultaneously on different threads and this causes the DependencyManager to ignore the addition of one of these two services (B). This causes the component to remain unsatisfied and never activate, since the service that was ignored is not re-registered at any time and nothing subsequently causes the component to re-activate. This happens as follows: 12:30:59:317 Thread 1 - Registers Service B/257 12:30:59:320 Thread 2 - Registers Service A/258 12:30:59:320 Thread 2 - Dependency Manager: Adding Service A/258 12:30:59:321 Thread 2 - Dependency Manager: Service serviceA registered, activate component 12:30:59:321 Thread 2 - State transition : Unsatisfied - Activating 12:30:59:321 Thread 2 - Activating component 12:30:59:321 Thread 1 - Dependency Manager: Adding Service B/257 12:30:59:321 Thread 2 - Dependency not satisfied: serviceB 12:30:59:321 Thread 1 - Dependency Manager: Added service serviceB is ignored for static reference --- I believe we end up here because Thread 2 has moved the component from Unsatisfied to Activating and the reference is a static reference 12:30:59:321 Thread 2 - Not all dependencies satisified, cannot activate 12:30:59:321 Thread 2 - State transition : Activating - Unsatisfied Because the addition of Service B has been ignored and serviceB is a required dependency my component then never activates even though my reqiured service is present. There is a comment in DependencyManager#serviceAdded method: // FELIX-1413: if the dependency is static and the component is // satisfied (active) added services are not considered until // the component is reactivated for other reasons. This suggests that the static service should only be ignored if the component is satisfied(active), which would be correct, but in this case the component is only activating (and will fail to activate because one of the two dependencies is not yet satisfied) and there is no check of state at this time. A simple fix would be to check the state of the component as well as if the service is static e.g. replace if ( m_dependencyMetadata.isStatic() ) with if ( m_dependencyMetadata.isStatic() m_componentManager.getState() == AbstractComponentManager.STATE_ACTIVE ) This is an easy fix, but I guess may leave a small window where a static reference could get replaced while a component was still activating if another instance of the same service was registered on a different thread. There are other fixes that could be done by synchronizing more around service additions. Is anyone willing to make this fix or does anyone have any thoughts about this issue? Thanks -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Commented] (FELIX-3456) Component ignores required static service addition when in Activating state
[ https://issues.apache.org/jira/browse/FELIX-3456?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13274780#comment-13274780 ] David Jencks commented on FELIX-3456: - I'm afraid I don't think the approach in FELIX-3456-fmeschbe.patch is workable. I have 3 main objections: 1. I don't think it is acceptable to return from a event that might have changed the state without doing the work. Thus I don't think any asynchronous processing is acceptable unless specifically mandated by the spec (as for enable/disable). One of my suggestions had a similar queue work we can't do right now approach and the results were too unpredictable. 2. A hardcoded wait time is a bad solution to the problem. You can avoid the fixed wait by using a lock with a timeout. Also this is a radically out of order proposal. In the half-second the state may have gone back and forth between e.g. active and inactive and enabled and disabled many times. 3. If you replace the delayAndCheck with a lock, or regard it as a new style of lock, the locks are too small. The locks should be around the entire event processing. The only part of the processing that can take any time is calling out to the framework and config admin, which has to happen in the locked region anyway. So locking the entire event processing won't take any longer and will make the effect of the code more possible to understand. Component ignores required static service addition when in Activating state --- Key: FELIX-3456 URL: https://issues.apache.org/jira/browse/FELIX-3456 Project: Felix Issue Type: Bug Components: Declarative Services (SCR) Affects Versions: scr-1.6.0 Environment: Using org.apache.felix.scr svn rev 1298268 on Mac Reporter: Richard Ellis Priority: Critical Attachments: FELIX-3456-1.1.diff, FELIX-3456-1.diff, FELIX-3456-3.diff, FELIX-3456-4.diff, FELIX-3456-fmeschbe.patch I have a component with two required static service references (A and B). In my scenario A and B are registered nearly simultaneously on different threads and this causes the DependencyManager to ignore the addition of one of these two services (B). This causes the component to remain unsatisfied and never activate, since the service that was ignored is not re-registered at any time and nothing subsequently causes the component to re-activate. This happens as follows: 12:30:59:317 Thread 1 - Registers Service B/257 12:30:59:320 Thread 2 - Registers Service A/258 12:30:59:320 Thread 2 - Dependency Manager: Adding Service A/258 12:30:59:321 Thread 2 - Dependency Manager: Service serviceA registered, activate component 12:30:59:321 Thread 2 - State transition : Unsatisfied - Activating 12:30:59:321 Thread 2 - Activating component 12:30:59:321 Thread 1 - Dependency Manager: Adding Service B/257 12:30:59:321 Thread 2 - Dependency not satisfied: serviceB 12:30:59:321 Thread 1 - Dependency Manager: Added service serviceB is ignored for static reference --- I believe we end up here because Thread 2 has moved the component from Unsatisfied to Activating and the reference is a static reference 12:30:59:321 Thread 2 - Not all dependencies satisified, cannot activate 12:30:59:321 Thread 2 - State transition : Activating - Unsatisfied Because the addition of Service B has been ignored and serviceB is a required dependency my component then never activates even though my reqiured service is present. There is a comment in DependencyManager#serviceAdded method: // FELIX-1413: if the dependency is static and the component is // satisfied (active) added services are not considered until // the component is reactivated for other reasons. This suggests that the static service should only be ignored if the component is satisfied(active), which would be correct, but in this case the component is only activating (and will fail to activate because one of the two dependencies is not yet satisfied) and there is no check of state at this time. A simple fix would be to check the state of the component as well as if the service is static e.g. replace if ( m_dependencyMetadata.isStatic() ) with if ( m_dependencyMetadata.isStatic() m_componentManager.getState() == AbstractComponentManager.STATE_ACTIVE ) This is an easy fix, but I guess may leave a small window where a static reference could get replaced while a component was still activating if another instance of the same service was registered on a different thread. There are other fixes that could be done by synchronizing more around service additions. Is anyone willing to make this fix or does anyone have any thoughts about this issue? Thanks -- This message is automatically generated by
[jira] [Commented] (FELIX-3456) Component ignores required static service addition when in Activating state
[ https://issues.apache.org/jira/browse/FELIX-3456?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13254080#comment-13254080 ] Felix Meschberger commented on FELIX-3456: -- A colleague tried a completely asynchronous model for service events in scr and although start seemed to work, stopping resulted in a lot of work on stopped bundles and component objects Been there done that ... SCR was fully asynchronous at one point in time. Stopping failed miserably because services have been gone when the component was about to be stopped and expected statically bound services to still be available. Startup worked correctly and the spec does not favor one or the other (I think there is nothing about synchronicity in the spec). I converted to synchronous startup to have better control during system startup (namely to have all components activated when the FRAMEWORK_STARTED event is fired by the framework). In fact, it is quite nice to have all components fuly handled once the bundle's STARTED or STOPPED event is fired. (This is one of my concerns with blueprint which is asynchronous and makes it hard to reason about system state). Overall and in hindsight it looks like synchronous startup is preferable to asynchronous startup. BTW: The last time I checked, Equinox DS was also fully synchronous. We might have an internal and external state. In your proposal thread 2 waits for the lock and thus thread 1 and thread 2 are susceptive to deadlocks. Particularly if you take another service into account The reason for this is, that when a service is supplied we are called back from the framework and thus have to be extremely carefull since the framework may still hold locks (for example bundle locks during bundle start) Component ignores required static service addition when in Activating state --- Key: FELIX-3456 URL: https://issues.apache.org/jira/browse/FELIX-3456 Project: Felix Issue Type: Bug Components: Declarative Services (SCR) Affects Versions: scr-1.6.0 Environment: Using org.apache.felix.scr svn rev 1298268 on Mac Reporter: Richard Ellis Priority: Critical Attachments: FELIX-3456-1.diff I have a component with two required static service references (A and B). In my scenario A and B are registered nearly simultaneously on different threads and this causes the DependencyManager to ignore the addition of one of these two services (B). This causes the component to remain unsatisfied and never activate, since the service that was ignored is not re-registered at any time and nothing subsequently causes the component to re-activate. This happens as follows: 12:30:59:317 Thread 1 - Registers Service B/257 12:30:59:320 Thread 2 - Registers Service A/258 12:30:59:320 Thread 2 - Dependency Manager: Adding Service A/258 12:30:59:321 Thread 2 - Dependency Manager: Service serviceA registered, activate component 12:30:59:321 Thread 2 - State transition : Unsatisfied - Activating 12:30:59:321 Thread 2 - Activating component 12:30:59:321 Thread 1 - Dependency Manager: Adding Service B/257 12:30:59:321 Thread 2 - Dependency not satisfied: serviceB 12:30:59:321 Thread 1 - Dependency Manager: Added service serviceB is ignored for static reference --- I believe we end up here because Thread 2 has moved the component from Unsatisfied to Activating and the reference is a static reference 12:30:59:321 Thread 2 - Not all dependencies satisified, cannot activate 12:30:59:321 Thread 2 - State transition : Activating - Unsatisfied Because the addition of Service B has been ignored and serviceB is a required dependency my component then never activates even though my reqiured service is present. There is a comment in DependencyManager#serviceAdded method: // FELIX-1413: if the dependency is static and the component is // satisfied (active) added services are not considered until // the component is reactivated for other reasons. This suggests that the static service should only be ignored if the component is satisfied(active), which would be correct, but in this case the component is only activating (and will fail to activate because one of the two dependencies is not yet satisfied) and there is no check of state at this time. A simple fix would be to check the state of the component as well as if the service is static e.g. replace if ( m_dependencyMetadata.isStatic() ) with if ( m_dependencyMetadata.isStatic() m_componentManager.getState() == AbstractComponentManager.STATE_ACTIVE ) This is an easy fix, but I guess may leave a small window where a static reference could get replaced while a component was still activating if another instance of the same
[jira] [Commented] (FELIX-3456) Component ignores required static service addition when in Activating state
[ https://issues.apache.org/jira/browse/FELIX-3456?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13253605#comment-13253605 ] Felix Meschberger commented on FELIX-3456: -- Thanks for reporting. This is in fact an issue. I am not against replacing the size int by an AtomicInteger; in the interest of concurrency stability this might make sense. (though this might prevent SCR from being used in pre-Java 5 setups; we still consider this requirement valid for SCR) But I am not convinced with the state lock. This going to be dangerous for deadlocks because during activate and deactive services may be registered or unregistered, which may cause deadlocks: We currently have one single situation where we synchronize (creation of delayed component service instances) and we realize occasional deadlocks. Thinking the other way around: We have some transient states during which events may happen which may get lost. One such transient state is the activating state. And this is such an event which may get lost. Another event may be a configuration update. I have been contemplating some kind of event queuing and some way of processing such a queue when leaving the transient state. In the concrete example: T1 registers Service A, causes component into the ACTIVATING state T2 registers Service B, enqueues event since component is ACTIVATING T1 terminates ACTIVATING, checks queue and handles event. The queue could be as simple as a list of Runnable on each component manager. Component ignores required static service addition when in Activating state --- Key: FELIX-3456 URL: https://issues.apache.org/jira/browse/FELIX-3456 Project: Felix Issue Type: Bug Components: Declarative Services (SCR) Affects Versions: scr-1.6.0 Environment: Using org.apache.felix.scr svn rev 1298268 on Mac Reporter: Richard Ellis Priority: Critical Attachments: FELIX-3456-1.diff I have a component with two required static service references (A and B). In my scenario A and B are registered nearly simultaneously on different threads and this causes the DependencyManager to ignore the addition of one of these two services (B). This causes the component to remain unsatisfied and never activate, since the service that was ignored is not re-registered at any time and nothing subsequently causes the component to re-activate. This happens as follows: 12:30:59:317 Thread 1 - Registers Service B/257 12:30:59:320 Thread 2 - Registers Service A/258 12:30:59:320 Thread 2 - Dependency Manager: Adding Service A/258 12:30:59:321 Thread 2 - Dependency Manager: Service serviceA registered, activate component 12:30:59:321 Thread 2 - State transition : Unsatisfied - Activating 12:30:59:321 Thread 2 - Activating component 12:30:59:321 Thread 1 - Dependency Manager: Adding Service B/257 12:30:59:321 Thread 2 - Dependency not satisfied: serviceB 12:30:59:321 Thread 1 - Dependency Manager: Added service serviceB is ignored for static reference --- I believe we end up here because Thread 2 has moved the component from Unsatisfied to Activating and the reference is a static reference 12:30:59:321 Thread 2 - Not all dependencies satisified, cannot activate 12:30:59:321 Thread 2 - State transition : Activating - Unsatisfied Because the addition of Service B has been ignored and serviceB is a required dependency my component then never activates even though my reqiured service is present. There is a comment in DependencyManager#serviceAdded method: // FELIX-1413: if the dependency is static and the component is // satisfied (active) added services are not considered until // the component is reactivated for other reasons. This suggests that the static service should only be ignored if the component is satisfied(active), which would be correct, but in this case the component is only activating (and will fail to activate because one of the two dependencies is not yet satisfied) and there is no check of state at this time. A simple fix would be to check the state of the component as well as if the service is static e.g. replace if ( m_dependencyMetadata.isStatic() ) with if ( m_dependencyMetadata.isStatic() m_componentManager.getState() == AbstractComponentManager.STATE_ACTIVE ) This is an easy fix, but I guess may leave a small window where a static reference could get replaced while a component was still activating if another instance of the same service was registered on a different thread. There are other fixes that could be done by synchronizing more around service additions. Is anyone willing to make this fix or does anyone have any thoughts about this issue? Thanks -- This message is automatically
[jira] [Commented] (FELIX-3456) Component ignores required static service addition when in Activating state
[ https://issues.apache.org/jira/browse/FELIX-3456?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13253938#comment-13253938 ] David Jencks commented on FELIX-3456: - Just in case anyone was wondering, as I was, I checked the spec and (4.3 section 5.3) all service events must be delivered synchronously. Thus there is definitely a possibility of deadlocks if we're not careful (more careful than my patch). A colleague tried a completely asynchronous model for service events in scr and although start seemed to work, stopping resulted in a lot of work on stopped bundles and component objects. I think if we can convince ourselves that it conforms to the spec this is a viable approach but it will take quite a bit of work to identify all the cases where we're working with closed stuff. I wonder to what extent we can remove the deadlock scenarios by (a) avoiding the synchronized block entirely when possible. For instance the first place we found this, DependencyManager.serviceAdded, I think we can skip the block I synchronized if the dependency is not mandatory, because if its not mandatory it showing up can't result in service activation. (b) avoiding calling out, such as the bind and unbind methods, from a synchronized block. This might be a wacky and non-plausible idea We might have an internal and external state. for instance: thread 1 supplies service A thread 1 gets the lock and updates internal and external state to activating thread 2 supplies service B and can't get the lock thread 1 does the calculations in Unsatisfied.activate up to the point where it calls out to the bind methods, and then updates the internal state to active and releases the lock thread 2 gets the lock and sees the internal state is active so it doesn't do much except release the lock thread 1 finishes calling the bind methods and updates the external state to active. Component ignores required static service addition when in Activating state --- Key: FELIX-3456 URL: https://issues.apache.org/jira/browse/FELIX-3456 Project: Felix Issue Type: Bug Components: Declarative Services (SCR) Affects Versions: scr-1.6.0 Environment: Using org.apache.felix.scr svn rev 1298268 on Mac Reporter: Richard Ellis Priority: Critical Attachments: FELIX-3456-1.diff I have a component with two required static service references (A and B). In my scenario A and B are registered nearly simultaneously on different threads and this causes the DependencyManager to ignore the addition of one of these two services (B). This causes the component to remain unsatisfied and never activate, since the service that was ignored is not re-registered at any time and nothing subsequently causes the component to re-activate. This happens as follows: 12:30:59:317 Thread 1 - Registers Service B/257 12:30:59:320 Thread 2 - Registers Service A/258 12:30:59:320 Thread 2 - Dependency Manager: Adding Service A/258 12:30:59:321 Thread 2 - Dependency Manager: Service serviceA registered, activate component 12:30:59:321 Thread 2 - State transition : Unsatisfied - Activating 12:30:59:321 Thread 2 - Activating component 12:30:59:321 Thread 1 - Dependency Manager: Adding Service B/257 12:30:59:321 Thread 2 - Dependency not satisfied: serviceB 12:30:59:321 Thread 1 - Dependency Manager: Added service serviceB is ignored for static reference --- I believe we end up here because Thread 2 has moved the component from Unsatisfied to Activating and the reference is a static reference 12:30:59:321 Thread 2 - Not all dependencies satisified, cannot activate 12:30:59:321 Thread 2 - State transition : Activating - Unsatisfied Because the addition of Service B has been ignored and serviceB is a required dependency my component then never activates even though my reqiured service is present. There is a comment in DependencyManager#serviceAdded method: // FELIX-1413: if the dependency is static and the component is // satisfied (active) added services are not considered until // the component is reactivated for other reasons. This suggests that the static service should only be ignored if the component is satisfied(active), which would be correct, but in this case the component is only activating (and will fail to activate because one of the two dependencies is not yet satisfied) and there is no check of state at this time. A simple fix would be to check the state of the component as well as if the service is static e.g. replace if ( m_dependencyMetadata.isStatic() ) with if ( m_dependencyMetadata.isStatic() m_componentManager.getState() == AbstractComponentManager.STATE_ACTIVE ) This is an easy fix, but I guess may leave a
[jira] [Commented] (FELIX-3456) Component ignores required static service addition when in Activating state
[ https://issues.apache.org/jira/browse/FELIX-3456?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13252637#comment-13252637 ] David Jencks commented on FELIX-3456: - After a very brief look I don't understand how this would result in correct behavior. I think that if the state is activating we would need to wait until it gets back to unsatisfied and then try activateInternal again. Otherwise won't we be binding the service but not checking if all the activation conditions are met? What will check and get the service to activate if all the conditions are now met? How about if there are 3 required services and we only have 2 of them? I think we need some thread synchronization and if the state is not unsatisified or active wait until it gets to one of those before proceeding. As I said this is after a very brief look, please think carefully before agreeing with me :-) Component ignores required static service addition when in Activating state --- Key: FELIX-3456 URL: https://issues.apache.org/jira/browse/FELIX-3456 Project: Felix Issue Type: Bug Components: Declarative Services (SCR) Affects Versions: scr-1.6.0 Environment: Using org.apache.felix.scr svn rev 1298268 on Mac Reporter: Richard Ellis Priority: Critical I have a component with two required static service references (A and B). In my scenario A and B are registered nearly simultaneously on different threads and this causes the DependencyManager to ignore the addition of one of these two services (B). This causes the component to remain unsatisfied and never activate, since the service that was ignored is not re-registered at any time and nothing subsequently causes the component to re-activate. This happens as follows: 12:30:59:317 Thread 1 - Registers Service B/257 12:30:59:320 Thread 2 - Registers Service A/258 12:30:59:320 Thread 2 - Dependency Manager: Adding Service A/258 12:30:59:321 Thread 2 - Dependency Manager: Service serviceA registered, activate component 12:30:59:321 Thread 2 - State transition : Unsatisfied - Activating 12:30:59:321 Thread 2 - Activating component 12:30:59:321 Thread 1 - Dependency Manager: Adding Service B/257 12:30:59:321 Thread 2 - Dependency not satisfied: serviceB 12:30:59:321 Thread 1 - Dependency Manager: Added service serviceB is ignored for static reference --- I believe we end up here because Thread 2 has moved the component from Unsatisfied to Activating and the reference is a static reference 12:30:59:321 Thread 2 - Not all dependencies satisified, cannot activate 12:30:59:321 Thread 2 - State transition : Activating - Unsatisfied Because the addition of Service B has been ignored and serviceB is a required dependency my component then never activates even though my reqiured service is present. There is a comment in DependencyManager#serviceAdded method: // FELIX-1413: if the dependency is static and the component is // satisfied (active) added services are not considered until // the component is reactivated for other reasons. This suggests that the static service should only be ignored if the component is satisfied(active), which would be correct, but in this case the component is only activating (and will fail to activate because one of the two dependencies is not yet satisfied) and there is no check of state at this time. A simple fix would be to check the state of the component as well as if the service is static e.g. replace if ( m_dependencyMetadata.isStatic() ) with if ( m_dependencyMetadata.isStatic() m_componentManager.getState() == AbstractComponentManager.STATE_ACTIVE ) This is an easy fix, but I guess may leave a small window where a static reference could get replaced while a component was still activating if another instance of the same service was registered on a different thread. There are other fixes that could be done by synchronizing more around service additions. Is anyone willing to make this fix or does anyone have any thoughts about this issue? Thanks -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Commented] (FELIX-3456) Component ignores required static service addition when in Activating state
[ https://issues.apache.org/jira/browse/FELIX-3456?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13252653#comment-13252653 ] Richard Ellis commented on FELIX-3456: -- On second thoughts I'm not sure my proposed fix goes far enough because even though it allows the second service to attempt to be bound, there is no guarantee that this bind operation will complete in a timely enough fashion for the activate process triggered by the first service to complete successfully. I think some synchronization will probably be required. Component ignores required static service addition when in Activating state --- Key: FELIX-3456 URL: https://issues.apache.org/jira/browse/FELIX-3456 Project: Felix Issue Type: Bug Components: Declarative Services (SCR) Affects Versions: scr-1.6.0 Environment: Using org.apache.felix.scr svn rev 1298268 on Mac Reporter: Richard Ellis Priority: Critical I have a component with two required static service references (A and B). In my scenario A and B are registered nearly simultaneously on different threads and this causes the DependencyManager to ignore the addition of one of these two services (B). This causes the component to remain unsatisfied and never activate, since the service that was ignored is not re-registered at any time and nothing subsequently causes the component to re-activate. This happens as follows: 12:30:59:317 Thread 1 - Registers Service B/257 12:30:59:320 Thread 2 - Registers Service A/258 12:30:59:320 Thread 2 - Dependency Manager: Adding Service A/258 12:30:59:321 Thread 2 - Dependency Manager: Service serviceA registered, activate component 12:30:59:321 Thread 2 - State transition : Unsatisfied - Activating 12:30:59:321 Thread 2 - Activating component 12:30:59:321 Thread 1 - Dependency Manager: Adding Service B/257 12:30:59:321 Thread 2 - Dependency not satisfied: serviceB 12:30:59:321 Thread 1 - Dependency Manager: Added service serviceB is ignored for static reference --- I believe we end up here because Thread 2 has moved the component from Unsatisfied to Activating and the reference is a static reference 12:30:59:321 Thread 2 - Not all dependencies satisified, cannot activate 12:30:59:321 Thread 2 - State transition : Activating - Unsatisfied Because the addition of Service B has been ignored and serviceB is a required dependency my component then never activates even though my reqiured service is present. There is a comment in DependencyManager#serviceAdded method: // FELIX-1413: if the dependency is static and the component is // satisfied (active) added services are not considered until // the component is reactivated for other reasons. This suggests that the static service should only be ignored if the component is satisfied(active), which would be correct, but in this case the component is only activating (and will fail to activate because one of the two dependencies is not yet satisfied) and there is no check of state at this time. A simple fix would be to check the state of the component as well as if the service is static e.g. replace if ( m_dependencyMetadata.isStatic() ) with if ( m_dependencyMetadata.isStatic() m_componentManager.getState() == AbstractComponentManager.STATE_ACTIVE ) This is an easy fix, but I guess may leave a small window where a static reference could get replaced while a component was still activating if another instance of the same service was registered on a different thread. There are other fixes that could be done by synchronizing more around service additions. Is anyone willing to make this fix or does anyone have any thoughts about this issue? Thanks -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira
[jira] [Commented] (FELIX-3456) Component ignores required static service addition when in Activating state
[ https://issues.apache.org/jira/browse/FELIX-3456?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanelfocusedCommentId=13252655#comment-13252655 ] Richard Ellis commented on FELIX-3456: -- If only my browser had refreshed faster I could have agreed with you already David instead of disagreeing with myself :) I do agree David, my hasty attempt at a fix without a full understanding of the code is not correct. Component ignores required static service addition when in Activating state --- Key: FELIX-3456 URL: https://issues.apache.org/jira/browse/FELIX-3456 Project: Felix Issue Type: Bug Components: Declarative Services (SCR) Affects Versions: scr-1.6.0 Environment: Using org.apache.felix.scr svn rev 1298268 on Mac Reporter: Richard Ellis Priority: Critical I have a component with two required static service references (A and B). In my scenario A and B are registered nearly simultaneously on different threads and this causes the DependencyManager to ignore the addition of one of these two services (B). This causes the component to remain unsatisfied and never activate, since the service that was ignored is not re-registered at any time and nothing subsequently causes the component to re-activate. This happens as follows: 12:30:59:317 Thread 1 - Registers Service B/257 12:30:59:320 Thread 2 - Registers Service A/258 12:30:59:320 Thread 2 - Dependency Manager: Adding Service A/258 12:30:59:321 Thread 2 - Dependency Manager: Service serviceA registered, activate component 12:30:59:321 Thread 2 - State transition : Unsatisfied - Activating 12:30:59:321 Thread 2 - Activating component 12:30:59:321 Thread 1 - Dependency Manager: Adding Service B/257 12:30:59:321 Thread 2 - Dependency not satisfied: serviceB 12:30:59:321 Thread 1 - Dependency Manager: Added service serviceB is ignored for static reference --- I believe we end up here because Thread 2 has moved the component from Unsatisfied to Activating and the reference is a static reference 12:30:59:321 Thread 2 - Not all dependencies satisified, cannot activate 12:30:59:321 Thread 2 - State transition : Activating - Unsatisfied Because the addition of Service B has been ignored and serviceB is a required dependency my component then never activates even though my reqiured service is present. There is a comment in DependencyManager#serviceAdded method: // FELIX-1413: if the dependency is static and the component is // satisfied (active) added services are not considered until // the component is reactivated for other reasons. This suggests that the static service should only be ignored if the component is satisfied(active), which would be correct, but in this case the component is only activating (and will fail to activate because one of the two dependencies is not yet satisfied) and there is no check of state at this time. A simple fix would be to check the state of the component as well as if the service is static e.g. replace if ( m_dependencyMetadata.isStatic() ) with if ( m_dependencyMetadata.isStatic() m_componentManager.getState() == AbstractComponentManager.STATE_ACTIVE ) This is an easy fix, but I guess may leave a small window where a static reference could get replaced while a component was still activating if another instance of the same service was registered on a different thread. There are other fixes that could be done by synchronizing more around service additions. Is anyone willing to make this fix or does anyone have any thoughts about this issue? Thanks -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira
