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Message re: MaxDirectMemorySize in Jazz logs / Change needed?
-XmxNg -XmsNg -XmnN/8m -Xgcpolicy:gencon -Xnocompressedrefs -XX:MaxDirectMemorySize=1G
Now I sometimes see errors mentioning:
Direct buffer memory::Please use appropriate '<size>' via -XX:MaxDirectMemorySize
[ very large stack trace omitted for brevity ]
Is there any action that ought to be considered here ?
One answer
Comments
There is no "caused by" in the stack trace. It does, however, start:
java.lang.OutOfMemoryError: Direct buffer memory::Please use appropriate '<size>' via -XX:MaxDirectMemorySize=<size>
at java.nio.Bits.reserveMemory(Bits.java:705)
at java.nio.DirectByteBuffer.<init>(DirectByteBuffer.java:109)
at java.nio.ByteBuffer.allocateDirect(ByteBuffer.java:299)
at com.ibm.ws.buffermgmt.impl.WsByteBufferPoolManagerImpl.allocateBufferDirect(WsByteBufferPoolManagerImpl.java:706)
at com.ibm.ws.buffermgmt.impl.WsByteBufferPoolManagerImpl.allocateCommon(WsByteBufferPoolManagerImpl.java:612)
at com.ibm.ws.buffermgmt.impl.WsByteBufferPoolManagerImpl.allocateDirect(WsByteBufferPoolManagerImpl.java:527)
at
It's indeed OutOfMemoryError. I would not suggest you increase MaxDirectMemorySize blindly. As mentioned earlier, please contact Support and get the GC verbose log analyzed.
This pre-supposes GC is turned on.
Yes. To diagnose memory/heap related issues, GC verbose has to be turned on. In fact, you can keep it on all the time and it only has little performance impact.
<gc-start id="91223" type="scavenge" contextid="91222" timestamp="2014-09-25T11:04:44.465">
<gc-start id="91235" type="scavenge" contextid="91234" timestamp="2014-09-25T11:04:49.598">
<gc-start id="91247" type="scavenge" contextid="91246" timestamp="2014-09-25T11:04:57.482">
<gc-start id="91259" type="scavenge" contextid="91258" timestamp="2014-09-25T11:05:08.605">
<gc-start id="91271" type="scavenge" contextid="91270" timestamp="2014-09-25T11:05:16.264">
<gc-start id="91283" type="scavenge" contextid="91282" timestamp="2014-09-25T11:05:24.033">
<gc-start id="91295" type="scavenge" contextid="91294" timestamp="2014-09-25T11:05:31.610">
Seems to be happening very frequently, that's just the tail end. Almost 8K occurrences.
That's quite normal for an active system. We are more interested with those with type="global". It will not be efficient to analyze a log file in a forum post and I suggest you open a tick with Support if you have not done so.
Adding the custom property described under Out of Memory in this article https://jazz.net/library/article/1430 has since Friday evening past and Saturday morning past relieved the occurrence of the Out of Memory exception ( i.e. none so far ).