Deven, CR number is 7164191 .
Could you re-send me your original e-mail with problem description and webrev link. I'll put it to CR comment field. -Dmitry On 2012-04-24 16:15, Dmitry Samersoff wrote: > Deven, > > After close look and off-line discussion with David Holmes, > the changes looks good for me. > > I'll take care of the rest. > > We have one more place in Agent.java executing exactly the same code > so I'll change both of them on your behalf. > > -Dmitry > > > On 2012-04-23 11:43, Deven You wrote: >> Thanks David, >> >> So is it ok for you to contribute this patch? >> >> On 04/23/2012 02:36 PM, David Holmes wrote: >>> Except of course that Properties is a Hashtable and synchronizes on >>> 'this' for all public methods. So locking the properties object in the >>> client code will guarantee exclusive access to it. >>> >>> Sorry about that. >>> >>> David >>> ----- >>> >>> On 23/04/2012 4:30 PM, David Holmes wrote: >>>> Deven, >>>> >>>> On 23/04/2012 3:54 PM, Deven You wrote: >>>>> On 04/18/2012 02:20 PM, Deven You wrote: >>>>>> On 04/18/2012 01:34 PM, Mandy Chung wrote: >>>>>>> >>>>>>> >>>>>>> I think this could still run into CME. System Properties is not a >>>>>>> synchronized map and the setter methods (System.setProperty or >>>>>>> Properties.put method) doesn't synchronize on the Properties object. >>>>>>> >>>>>>> >>>>>>> The setter methods I'm referring to are System.setProperty and >>>>>>> System.getProperties().put(). >>>>>>> >>>>>> >>>>>> I have gone through the Agent.java, I think other set/put methods >>>>>> related to properties are protected properly. >>>>>> >>>>>> public static void agentmain using parseString(args) which return a >>>>>> properties which is a local var and is not possible to cause >>>>>> concurrent problem when call config_props.putAll(arg_props). >>>>>> >>>>>> private static synchronized void startLocalManagementAgent() is >>>>>> synchronized already. >>>>>> >>>>>> private static synchronized void startRemoteManagementAgent(String >>>>>> args) is synchronized also. >>>>>> >>>>>> Could you point where the CME may ocurr? >>>>> >>>>> Is there any suggestion from the mailing list? >>>> >>>> The problem is that System.getProperties() returns a globally >>>> accessible >>>> set of properties. So even if you prevent the Agent code from modifying >>>> those properties concurrently with other use in the Agent, you have no >>>> such guard for any other piece of code in the system which might also >>>> modify the properties. So the race condition you were trying to fix >>>> still exists. I don't see any way to fix this. No matter what you do >>>> another thread can modify the system properties while you are iterating >>>> them. Instead you need to anticipate the CME and try to recover from it >>>> (also non-trivial). >>>> >>>> Cheers, >>>> David Holmes >>> >> >> > > -- Dmitry Samersoff Java Hotspot development team, SPB04 * There will come soft rains ...
