OOM Exceptions during startup

Flowable Engine
1

Hello,
I am running Flowable on an EC2 instance (m4.large) with 2 vCPU and 8 GB RAM. It was performing without any glitch until I now - when I am unable to boot the Tomcat8 server running Flowable.
I continuously see these OutOfMemoryError: Java heap space exceptions.

Any suggestions on how I can debug and fix these exceptions? Is there an recommended hardware configuration that is recommended OR a type of EC2 instance that is recommended?

Exception in thread "flowable-acquire-timer-jobs" java.lang.OutOfMemoryError: Java heap space
Exception in thread "flowable-reset-expired-jobs" java.lang.OutOfMemoryError: Java heap space

Exception: java.lang.OutOfMemoryError thrown from the UncaughtExceptionHandler in thread "Abandoned connection cleanup thread"
Oct 22, 2017 2:45:13 PM org.apache.catalina.startup.HostConfig deployWAR
INFO: Deploying web application archive /var/lib/tomcat8/webapps/flowable-idm.war
Oct 22, 2017 2:45:13 PM org.apache.catalina.startup.HostConfig deployWARs
SEVERE: Error waiting for multi-thread deployment of WAR files to complete
java.util.concurrent.ExecutionException: java.lang.OutOfMemoryError: Java heap space
        at java.util.concurrent.FutureTask.report(FutureTask.java:122)
        at java.util.concurrent.FutureTask.get(FutureTask.java:192)
        at org.apache.catalina.startup.HostConfig.deployWARs(HostConfig.java:731)
        at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:400)
        at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1542)
        at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:286)
        at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:95)
        at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90)
        at org.apache.catalina.util.LifecycleBase.setStateInternal(LifecycleBase.java:394)
        at org.apache.catalina.util.LifecycleBase.setState(LifecycleBase.java:339)
        at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:933)
        at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:871)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)
        at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1408)
        at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1398)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.OutOfMemoryError: Java heap space

Oct 22, 2017 2:45:18 PM org.apache.catalina.startup.HostConfig deployWARs
SEVERE: Error waiting for multi-thread deployment of WAR files to complete
java.util.concurrent.ExecutionException: java.lang.OutOfMemoryError: Java heap space
        at java.util.concurrent.FutureTask.report(FutureTask.java:122)
        at java.util.concurrent.FutureTask.get(FutureTask.java:192)
        at org.apache.catalina.startup.HostConfig.deployWARs(HostConfig.java:731)
        at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:400)
        at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1542)
        at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:286)
        at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:95)
        at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90)
        at org.apache.catalina.util.LifecycleBase.setStateInternal(LifecycleBase.java:394)
        at org.apache.catalina.util.LifecycleBase.setState(LifecycleBase.java:339)
        at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:933)
        at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:871)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)
        at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1408)
        at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1398)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.OutOfMemoryError: Java heap space

Oct 22, 2017 2:45:20 PM org.apache.catalina.startup.HostConfig deployDirectory
INFO: Deploying web application directory /var/lib/tomcat8/webapps/ROOT
Oct 22, 2017 2:45:27 PM org.apache.catalina.startup.HostConfig deployDirectories
SEVERE: Error waiting for multi-thread deployment of directories to complete
java.util.concurrent.ExecutionException: java.lang.OutOfMemoryError: Java heap space
        at java.util.concurrent.FutureTask.report(FutureTask.java:122)
        at java.util.concurrent.FutureTask.get(FutureTask.java:192)
        at org.apache.catalina.startup.HostConfig.deployDirectories(HostConfig.java:1010)
        at org.apache.catalina.startup.HostConfig.deployApps(HostConfig.java:402)
        at org.apache.catalina.startup.HostConfig.start(HostConfig.java:1542)
        at org.apache.catalina.startup.HostConfig.lifecycleEvent(HostConfig.java:286)
        at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:95)
        at org.apache.catalina.util.LifecycleBase.fireLifecycleEvent(LifecycleBase.java:90)
        at org.apache.catalina.util.LifecycleBase.setStateInternal(LifecycleBase.java:394)
        at org.apache.catalina.util.LifecycleBase.setState(LifecycleBase.java:339)
        at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:933)
        at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:871)
        at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:147)
        at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1408)
        at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1398)
        at java.util.concurrent.FutureTask.run(FutureTask.java:266)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
        at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.OutOfMemoryError: Java heap space

Oct 22, 2017 2:45:33 PM org.apache.coyote.AbstractProtocol start
INFO: Starting ProtocolHandler ["http-nio-8080"]
2

Just to clarify, there is about 7 GiB of free memory and 4.2GiB of diskspace (without swap) to say that there is plenty of resources available when this happens.

3

Hi,

Did you increase the memory settings of Tomcat 8?
You could try to increase the values of -Xms, -Xmx and -XX:PermSize.
That the EC2 instance has a lot of free memory doesn’t say anything, because Tomcat will use the -Xms, -Xmx and -XX:PermSize values.

Best regards,

Tijs

4

Thanks @tijs,
Increasing the values of -Xms, -Xmx and -XX:PermSize fixed the issue.