Valentin, I did test on demo web app where HttpSession is backed by Ignite cache and collect some logs. There are many places in Ignite where thread locals are used. Then cache methods are accessed in threads from servlet container pool, we get leaks. I don't think it will be easy to add thread locals cleaning in all these places without major code rewrite, but, for sure, it would be ideal solution.
<E0><EF><F0> 05, 2016 4:21:52 PM org.apache.catalina.loader.WebappClassLoaderBase checkThreadLocalMapForLeaks SEVERE: The web application [/app1] created a ThreadLocal with key of type [org.apache.ignite.internal.util.GridSpinReadWriteLock$1] (value [org.apache.ignite.internal.util.GridSpinReadWriteLock$1@5fecc35f]) and a value of type [java.lang.Integer] (value [0]) but failed to remove it when the web application was stopped. Threads are going to be renewed over time to try and avoid a probable memory leak. <E0><EF><F0> 05, 2016 4:21:52 PM org.apache.catalina.loader.WebappClassLoaderBase checkThreadLocalMapForLeaks SEVERE: The web application [/app1] created a ThreadLocal with key of type [org.apache.ignite.internal.util.tostring.GridToStringBuilder$1] (value [org.apache.ignite.internal.util.tostring.GridToStringBuilder$1@4ecdfc04]) and a value of type [java.util.LinkedList] (value [[org.apache.ignite.internal.util.tostring.GridToStringThreadLocal@684a2791]]) but failed to remove it when the web application was stopped. Threads are going to be renewed over time to try and avoid a probable memory leak. <E0><EF><F0> 05, 2016 4:21:52 PM org.apache.catalina.loader.WebappClassLoaderBase checkThreadLocalMapForLeaks SEVERE: The web application [/app1] created a ThreadLocal with key of type [org.apache.ignite.internal.binary.BinaryThreadLocalContext$1] (value [org.apache.ignite.internal.binary.BinaryThreadLocalContext$1@4e9300e7]) and a value of type [org.apache.ignite.internal.binary.BinaryThreadLocalContext] (value [org.apache.ignite.internal.binary.BinaryThreadLocalContext@7934a88]) but failed to remove it when the web application was stopped. Threads are going to be renewed over time to try and avoid a probable memory leak. <E0><EF><F0> 05, 2016 4:21:52 PM org.apache.catalina.loader.WebappClassLoaderBase checkThreadLocalMapForLeaks SEVERE: The web application [/app1] created a ThreadLocal with key of type [java.lang.ThreadLocal] (value [java.lang.ThreadLocal@56502b72]) and a value of type [org.apache.ignite.internal.binary.streams.BinaryMemoryAllocatorChunk] (value [org.apache.ignite.internal.binary.streams.BinaryMemoryAllocatorChunk@4eab9d2f]) but failed to remove it when the web application was stopped. Threads are going to be renewed over time to try and avoid a probable memory leak. <E0><EF><F0> 05, 2016 4:21:52 PM org.apache.catalina.loader.WebappClassLoaderBase checkThreadLocalMapForLeaks SEVERE: The web application [/app1] created a ThreadLocal with key of type [java.lang.ThreadLocal] (value [java.lang.ThreadLocal@eb53c9d]) and a value of type [org.apache.ignite.marshaller.optimized.OptimizedObjectStreamRegistry.StreamHolder] (value [org.apache.ignite.marshaller.optimized.OptimizedObjectStreamRegistry$StreamHolder@5e2c15f7]) but failed to remove it when the web application was stopped. Threads are going to be renewed over time to try and avoid a probable memory leak. <E0><EF><F0> 05, 2016 4:21:52 PM org.apache.catalina.loader.WebappClassLoaderBase checkThreadLocalMapForLeaks SEVERE: The web application [/app1] created a ThreadLocal with key of type [org.apache.ignite.internal.util.GridSpinReadWriteLock$1] (value [org.apache.ignite.internal.util.GridSpinReadWriteLock$1@55b9da28]) and a value of type [java.lang.Integer] (value [0]) but failed to remove it when the web application was stopped. Threads are going to be renewed over time to try and avoid a probable memory leak. <E0><EF><F0> 05, 2016 4:21:52 PM org.apache.catalina.loader.WebappClassLoaderBase checkThreadLocalMapForLeaks SEVERE: The web application [/app1] created a ThreadLocal with key of type [org.apache.ignite.internal.util.StripedCompositeReadWriteLock$1] (value [org.apache.ignite.internal.util.StripedCompositeReadWriteLock$1@1ac73431]) and a value of type [java.lang.Integer] (value [9]) but failed to remove it when the web application was stopped. Threads are going to be renewed over time to try and avoid a probable memory leak. SEVERE: The web application [/app1] created a ThreadLocal with key of type [org.apache.ignite.internal.processors.cache.GridCacheAdapter$5] (value [org.apache.ignite.internal.processors.cache.GridCacheAdapter$5@28a1bd99]) and a value of type [org.apache.ignite.internal.processors.cache.GridCacheAdapter.FutureHolder] (value [org.apache.ignite.internal.processors.cache.GridCacheAdapter$FutureHolder@6763d70c]) but failed to remove it when the web application was stopped. Threads are going to be renewed over time to try and avoid a probable memory leak. As a solution, I propose to implement servlet filter as a part of Ignite web integration, which will be responsible for cleaning up all thread locals after request processing. Filter must be executed last in filter chain to work correctly. It is not necessary to use the filter in case of Tomcat, because it provides own solution to the problem requiring special configuration parameter for context User should decide which approach is better to him. 2016-04-06 1:45 GMT+03:00 Valentin Kulichenko <[email protected] >: > Alexei, > > I would start with defining which thread locals cause this and why they are > not properly cleaned on node shutdown. Ideally, this should never happen. > > -Val > > On Tue, Apr 5, 2016 at 10:36 AM, Alexei Scherbakov < > [email protected]> wrote: > > > Hello. > > > > Currently I'm working on the IGNITE-967 > > <https://issues.apache.org/jira/browse/IGNITE-967>. > > > > In fact, it is well known, easily reproduceable, ClassLoader memory leak > > problem in managed environments, such as servlet containers. > > See http://wiki.apache.org/tomcat/MemoryLeakProtection to read more on > > that. > > In short, the code using thread locals is responsible for cleaning them > > after request processing > > to prevent memory leaks related to different lifetime of application and > > thread in pool. > > Also blindly reusing thread from pool can be dangerous, because current > > ThreadLocal value can be different from expected default value. > > > > One posiible way of solving the problem is using post-processing Filter, > > which is responsible for cleaning all thread locals on current thread. > > > > Another approach would be sticking with container's specific solution to > > this problem. > > On example, tomcat provides the configuration property > > renewThreadsWhenStoppingContext, > > which forces it to renew threads involved in servicing requests for > > destroyed context, thus removing leaks. > > > > What do you think? > > > > > > -- > > > > Best regards, > > Alexei Scherbakov > > > -- Best regards, Alexei Scherbakov
