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https://issues.apache.org/jira/browse/CLOUDSTACK-9595?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15665209#comment-15665209
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ASF GitHub Bot commented on CLOUDSTACK-9595:
--------------------------------------------
Github user jburwell commented on the issue:
https://github.com/apache/cloudstack/pull/1762
@serg38 that is not a safe assumption. Transactions often span multiple
statements and methods across DAOs. `TransactionLegacy` has a transaction
stacking/nested model that further occludes when a transaction actually
completely.
Deadlocks are a severe problem that need to be fixed. Unfortunately, this
patch would do more harm than good as it would eventually corrupt the database.
In, and of themselves, retries are also a very expensive solution to the
problem both in terms of the engineering effort required to do it properly and
the extra stress placed on the database to perform additional work that will
likely fail. Furthermore, a generic **and** correct retry mechanism is a very
difficult thing to write. Given the way transaction boundaries are managed in
ACS, I think such an effort would be nearly impossible.
In a properly written application, deadlocks should very rarely, if ever,
occur. Their presence is a symptom of improper transaction handling and/or
poor lock management problems. Therefore, my suggestion is that we change
this patch to log details about the context in which deadlocks occur. We can
then use this information to identify the areas in ACS where these contention
problems are location and fix the root cause.
> Transactions are not getting retried in case of database deadlock errors
> ------------------------------------------------------------------------
>
> Key: CLOUDSTACK-9595
> URL: https://issues.apache.org/jira/browse/CLOUDSTACK-9595
> Project: CloudStack
> Issue Type: Bug
> Security Level: Public(Anyone can view this level - this is the
> default.)
> Affects Versions: 4.8.0
> Reporter: subhash yedugundla
> Fix For: 4.8.1
>
>
> Customer is seeing occasional error 'Deadlock found when trying to get lock;
> try restarting transaction' messages in their management server logs. It
> happens regularly at least once a day. The following is the error seen
> 2015-12-09 19:23:19,450 ERROR [cloud.api.ApiServer]
> (catalina-exec-3:ctx-f05c58fc ctx-39c17156 ctx-7becdf6e) unhandled exception
> executing api command: [Ljava.lang.String;@230a6e7f
> com.cloud.utils.exception.CloudRuntimeException: DB Exception on:
> com.mysql.jdbc.JDBC4PreparedStatement@74f134e3: DELETE FROM
> instance_group_vm_map WHERE instance_group_vm_map.instance_id = 941374
> at com.cloud.utils.db.GenericDaoBase.expunge(GenericDaoBase.java:1209)
> at sun.reflect.GeneratedMethodAccessor360.invoke(Unknown Source)
> at
> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
> at java.lang.reflect.Method.invoke(Method.java:606)
> at
> org.springframework.aop.support.AopUtils.invokeJoinpointUsingReflection(AopUtils.java:317)
> at
> org.springframework.aop.framework.ReflectiveMethodInvocation.invokeJoinpoint(ReflectiveMethodInvocation.java:183)
> at
> org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
> at
> com.cloud.utils.db.TransactionContextInterceptor.invoke(TransactionContextInterceptor.java:34)
> at
> org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:161)
> at
> org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:91)
> at
> org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
> at
> org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:204)
> at com.sun.proxy.$Proxy237.expunge(Unknown Source)
> at
> com.cloud.vm.UserVmManagerImpl$2.doInTransactionWithoutResult(UserVmManagerImpl.java:2593)
> at
> com.cloud.utils.db.TransactionCallbackNoReturn.doInTransaction(TransactionCallbackNoReturn.java:25)
> at com.cloud.utils.db.Transaction$2.doInTransaction(Transaction.java:57)
> at com.cloud.utils.db.Transaction.execute(Transaction.java:45)
> at com.cloud.utils.db.Transaction.execute(Transaction.java:54)
> at
> com.cloud.vm.UserVmManagerImpl.addInstanceToGroup(UserVmManagerImpl.java:2575)
> at
> com.cloud.vm.UserVmManagerImpl.updateVirtualMachine(UserVmManagerImpl.java:2332)
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