Those are raw threads.
And are pointing to the Thread.contextClassLoader.
That's not a place a pinned classloader occurs.

Look for something in your webapp's own classes that has a reference to the
WebAppClassLoader.
The folks at Eclipse MAT have talked about this approach using their MAT
project.
https://www.eclipse.org/forums/index.php/t/205797/

Mark Thomas (from the tomcat project that also has this problem with hot
deploy) has also documented many Java and Javax classes that have this
classloader pinning / memory leak as well.
https://github.com/markt-asf/memory-leaks/tree/master/src/org/apache/markt/leaks

Joakim Erdfelt / [email protected]


On Fri, Jun 26, 2020 at 3:33 PM Kiao Desouzza <[email protected]>
wrote:

> I fired off profiler.
>
> After couple of uploads of WAR file:
> https://imgur.com/a/1BNM1fr
>
> One of the threads that shows as GC root for stale web app class loader:
> https://imgur.com/a/U9s4Y0V
>
> ... now i hope i have something useful.
>
> Regards
>
> On Fri, Jun 26, 2020 at 3:36 PM Jan Bartel <[email protected]> wrote:
>
>> I wonder if this is the same issue that was reported a few years ago,
>> that we could never get to the bottom of:
>> https://github.com/eclipse/jetty.project/issues/1425
>>
>> Jan
>>
>> On Fri, 26 Jun 2020 at 15:06, Joakim Erdfelt <[email protected]> wrote:
>>
>>> Hot reload on Java has many pitfalls.
>>>
>>> Most of them come from WebApp ClassLoader Pinning.
>>> Where a class being loaded from the WebApp is keeping a reference to the
>>> WebApp ClassLoader, preventing it from being recycled.
>>>
>>> We have many LeakPreventers implemented that prevent the WebApp
>>> ClassLoader Pinning, for the common JVM and Servlet/Java EE classes, but
>>> there are still more in various other 3rd party libraries.
>>>
>>> See
>>> https://www.eclipse.org/jetty/documentation/current/preventing-memory-leaks.html
>>>
>>> Give them a try, if it works out for you GREAT.
>>> But if you still have this issue, then you'll have to figure out which
>>> class is holding the reference to the WebAppClassLoader and perhaps
>>> implement a LeakPreventere for it to let you have hot reload success.
>>>
>>> Joakim Erdfelt / [email protected]
>>>
>>>
>>> On Fri, Jun 26, 2020 at 7:54 AM Kiao Desouzza <[email protected]>
>>> wrote:
>>>
>>>> Hi,
>>>>
>>>> I am having an issue with file system quota tools not reporting
>>>> correctly on the directory where jetty is deployed. After some
>>>> investigation I think it's down to left over file descriptors like these
>>>> (output from lsof):
>>>>
>>>> java      39467                 sclient    5r      REG
>>>>  8,1    134017  101365281
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/HikariCP-java7-2.4.13.jar
>>>> (deleted)
>>>> java      39467                 sclient    5r      REG
>>>>  8,1    134017  101365281
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/HikariCP-java7-2.4.13.jar
>>>> (deleted)
>>>> java      39467                 sclient   45r      REG
>>>>  8,1     69409  101365257
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/activation-1.1.1.jar
>>>> (deleted)
>>>> java      39467                 sclient   46r      REG
>>>>  8,1    267827  101365259
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/admin_2.13.jar
>>>> (deleted)
>>>> java      39467                 sclient   47r      REG
>>>>  8,1    499844  101365280
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/c3p0-0.9.5.4.jar
>>>> (deleted)
>>>> java      39467                 sclient   48r      REG
>>>>  8,1    246918  101365265
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/commons-beanutils-1.9.4.jar
>>>> (deleted)
>>>> java      39467                 sclient   49r      REG
>>>>  8,1    347669  101365260
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/commons-codec-1.14.jar
>>>> (deleted)
>>>> java      39467                 sclient   50r      REG
>>>>  8,1    588337  101365276
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/commons-collections-3.2.2.jar
>>>> (deleted)
>>>> java      39467                 sclient   51r      REG
>>>>  8,1    208475  101365250
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/commons-dbcp2-2.7.0.jar
>>>> (deleted)
>>>> java      39467                 sclient   52r      REG
>>>>  8,1    146108  101365282
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/commons-digester-1.8.1.jar
>>>> (deleted)
>>>> java      39467                 sclient   53r      REG
>>>>  8,1    214788  101365256
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/commons-io-2.6.jar
>>>> (deleted)
>>>> java      39467                 sclient   54r      REG
>>>>  8,1     61829  101365278
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/commons-logging-1.2.jar
>>>> (deleted)
>>>> java      39467                 sclient   55r      REG
>>>>  8,1    129592  101365268
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/commons-pool2-2.7.0.jar
>>>> (deleted)
>>>> java      39467                 sclient   56r      REG
>>>>  8,1    186077  102297951
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/commons-validator-1.6.jar
>>>> (deleted)
>>>> java      39467                 sclient   57r      REG
>>>>  8,1    580870  101365271
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/flyway-core-6.3.3.jar
>>>> (deleted)
>>>> java      39467                 sclient   58r      REG
>>>>  8,1   1586948  101365273
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/freemarker-2.3.29.jar
>>>> (deleted)
>>>> java      39467                 sclient   59r      REG
>>>>  8,1     80511  101365272
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/geny_2.13-0.6.0.jar
>>>> (deleted)
>>>> java      39467                 sclient   60r      REG
>>>>  8,1    219146  101365253
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/javax.mail-api-1.6.2.jar
>>>> (deleted)
>>>> java      39467                 sclient   61r      REG
>>>>  8,1     25464  101365283
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/jetty-continuation-9.4.28.v20200408.jar
>>>> (deleted)
>>>> java      39467                 sclient   62r      REG
>>>>  8,1    624036  101365275
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/mchange-commons-java-0.2.15.jar
>>>> (deleted)
>>>> java      39467                 sclient   63r      REG
>>>>  8,1    927447  101365252
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/postgresql-42.2.10.jar
>>>> (deleted)
>>>> java      39467                 sclient   64r      REG
>>>>  8,1    134017    1352185
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-17785782056536538882.dir/webapp/WEB-INF/lib/HikariCP-java7-2.4.13.jar
>>>> (deleted)
>>>> java      39467                 sclient   65r      REG
>>>>  8,1      4250  101365255
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/scala-collection-compat_2.13-2.1.6.jar
>>>> (deleted)
>>>> java      39467                 sclient   66r      REG
>>>>  8,1   5865349  101365264
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/scala-library-2.13.2.jar
>>>> (deleted)
>>>> java      39467                 sclient   67r      REG
>>>>  8,1    225338  101365277
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/scala-parser-combinators_2.13-1.1.2.jar
>>>> (deleted)
>>>> java      39467                 sclient   68r      REG
>>>>  8,1    129113  101365279
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/scalaj-http_2.13-2.4.2.jar
>>>> (deleted)
>>>> java      39467                 sclient   69r      REG
>>>>  8,1   3625052  101365254
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/scala-reflect-2.13.2.jar
>>>> (deleted)
>>>> java      39467                 sclient   70r      REG
>>>>  8,1   1801315  101365266
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/scalikejdbc-core_2.13-3.4.2.jar
>>>> (deleted)
>>>> java      39467                 sclient   71r      REG
>>>>  8,1      6504  102297938
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/scalikejdbc-interpolation-macro_2.13-3.4.2.jar
>>>> (deleted)
>>>> java      39467                 sclient   72r      REG
>>>>  8,1    201322  101365263
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/scalikejdbc-interpolation_2.13-3.4.2.jar
>>>> (deleted)
>>>> java      39467                 sclient   73r      REG
>>>>  8,1     19036  101365261
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/scalikejdbc_2.13-3.4.2.jar
>>>> (deleted)
>>>> java      39467                 sclient   74r      REG
>>>>  8,1     41472  101365274
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/slf4j-api-1.7.30.jar
>>>> (deleted)
>>>> java      39467                 sclient   75r      REG
>>>>  8,1     35063  101365284
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/stats_collector_2.13-0.1.0-SNAPSHOT.jar
>>>> (deleted)
>>>> java      39467                 sclient   76r      REG
>>>>  8,1    187761  101365270
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/ujson_2.13-1.1.0.jar
>>>> (deleted)
>>>> java      39467                 sclient   77r      REG
>>>>  8,1    114284  101365269
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-1577458225866104653.dir/webapp/WEB-INF/lib/upickle-core_2.13-1.1.0.jar
>>>> (deleted)
>>>> java      39467                 sclient   94r      REG
>>>>  8,1     69409    1220495
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-17785782056536538882.dir/webapp/WEB-INF/lib/activation-1.1.1.jar
>>>> (deleted)
>>>> java      39467                 sclient   95r      REG
>>>>  8,1    267827    1352165
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-17785782056536538882.dir/webapp/WEB-INF/lib/admin_2.13.jar
>>>> (deleted)
>>>> java      39467                 sclient   96r      REG
>>>>  8,1    499844    1352184
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-17785782056536538882.dir/webapp/WEB-INF/lib/c3p0-0.9.5.4.jar
>>>> (deleted)
>>>> java      39467                 sclient   97r      REG
>>>>  8,1    246918    1352170
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-17785782056536538882.dir/webapp/WEB-INF/lib/commons-beanutils-1.9.4.jar
>>>> (deleted)
>>>> java      39467                 sclient   98r      REG
>>>>  8,1    347669    1352166
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-17785782056536538882.dir/webapp/WEB-INF/lib/commons-codec-1.14.jar
>>>> (deleted)
>>>> java      39467                 sclient   99r      REG
>>>>  8,1    588337    1352180
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-17785782056536538882.dir/webapp/WEB-INF/lib/commons-collections-3.2.2.jar
>>>> (deleted)
>>>> java      39467                 sclient  100r      REG
>>>>  8,1    208475     957623
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-17785782056536538882.dir/webapp/WEB-INF/lib/commons-dbcp2-2.7.0.jar
>>>> (deleted)
>>>> java      39467                 sclient  101r      REG
>>>>  8,1    146108    1352186
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-17785782056536538882.dir/webapp/WEB-INF/lib/commons-digester-1.8.1.jar
>>>> (deleted)
>>>> java      39467                 sclient  102r      REG
>>>>  8,1    214788    1212954
>>>> /home/client/tmp/jetty-0_0_0_0-8443-root_war-_-any-17785782056536538882.dir/webapp/WEB-INF/lib/commons-io-2.6.jar
>>>> (deleted)
>>>> ...
>>>>
>>>> The file system tools(du) correctly report used disk space but file
>>>> system quota is not seeing space being released after each update of
>>>> deployed WAR file (used space grows). After I restart jetty file system
>>>> quota is updated correctly. It's only JAR files from what I can tell so
>>>> could it be related to the class loader in some way?
>>>>
>>>> FS is xfs on centos8 with pquota (project quota)
>>>>
>>>> I am using latest release 9.4.30.v20200611
>>>>
>>>> Regards
>>>> _______________________________________________
>>>> jetty-users mailing list
>>>> [email protected]
>>>> To unsubscribe from this list, visit
>>>> https://www.eclipse.org/mailman/listinfo/jetty-users
>>>>
>>> _______________________________________________
>>> jetty-users mailing list
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>>> To unsubscribe from this list, visit
>>> https://www.eclipse.org/mailman/listinfo/jetty-users
>>>
>>
>>
>> --
>> Jan Bartel <[email protected]>
>> www.webtide.com
>> *Expert assistance from the creators of Jetty and CometD*
>>
>> _______________________________________________
>> jetty-users mailing list
>> [email protected]
>> To unsubscribe from this list, visit
>> https://www.eclipse.org/mailman/listinfo/jetty-users
>>
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