Max possible heap size for Concurrent Mark Sweep collector.

[Alexey Ragozin]

Hi,

Sometimes ago we have tried to setup 200GiB heap per JVM using CMS GC.
Oracle HotSpot JVM have failed to start with following error

Java HotSpot(TM) 64-Bit Server VM warning: CMS bit map allocation failure
Java HotSpot(TM) 64-Bit Server VM warning: Failed to allocate CMS Bit Map
Error occurred during initialization of VM
Could not create CMS collector
Error: Could not create the Java Virtual Machine.
Error: A fatal exception has occurred. Program will exit.

JVM command line

/usr/java/jdk1.7.0_60/bin/java -d64 -verbose:gc -XX:+UseConcMarkSweepGC
-XX:+PrintGCDetails -XX:+PrintGCTimeStamps -Xmn512m
-XX:MaxTenuringThreshold=1 -Xms200G -Xmx200G
-XX:+UseCMSInitiatingOccupancyOnly -XX:CMSInitiatingOccupancyFraction=90
-Duse-cached-field-op=false  -XX:MaxPermSize=1024m
-Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote.port=13521
-Dcom.sun.management.jmxremote.authenticate=false
-Dcom.sun.management.jmxremote.ssl=false -XX:-UsePopCountInstruction
APPLICATION_MAIN_CLASS ...

We have reduced -Xmx to 180GiB and currently that is our configuration.
Provided amount of memory on our standard hardware setup, using JVM with
400 GiB would be desirable.

My question is

Is that 200GiB fundamental limitation of CMS algorithm or it is something
what could be remedied?

Any relevant pointers to open JDK code base would be appreciated.

Regards,
Alexey
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