Re: [ovirt-users] Can I reduce the Java heap size of engine-backup???

On Tue, Dec 29, 2015 at 12:51 AM, John Florian <jflorian(a)doubledog.org&gt; wrote: > I'm trying to run the engine-backup script via a Bacula job using the > RunScript option so that the engine-backup dumps its output someplace > where Bacula will collect it once engine-backup finishes. However the > job is failing and with enough digging I eventually learned the script > was writing the following in /tmp/hs_err_pid5789.log: > > # > # There is insufficient memory for the Java Runtime Environment to continue. > # Native memory allocation (mmap) failed to map 2555904 bytes for > committing reserved memory. > # Possible reasons: > # The system is out of physical RAM or swap space > # In 32 bit mode, the process size limit was hit > # Possible solutions: > # Reduce memory load on the system > # Increase physical memory or swap space > # Check if swap backing store is full > # Use 64 bit Java on a 64 bit OS > # Decrease Java heap size (-Xmx/-Xms) > # Decrease number of Java threads > # Decrease Java thread stack sizes (-Xss) > # Set larger code cache with -XX:ReservedCodeCacheSize= > # This output file may be truncated or incomplete. > # > # Out of Memory Error (os_linux.cpp:2627), pid=5789, tid=140709998221056 > # > # JRE version: (8.0_65-b17) (build ) > # Java VM: OpenJDK 64-Bit Server VM (25.65-b01 mixed mode linux-amd64 > compressed oops) > # Failed to write core dump. Core dumps have been disabled. To enable > core dumping, try "ulimit -c unlimited" before starting Java again > # > > > So is there any good way to reduce the Java heap size? I mean I know > what -Xmx does, but where might I try setting it, ideally so that it > affects the engine-backup only? Any idea of good setting for a very > small environment with a dozen VMs? engine-backup does not directly call nor need java. AFAICS it only calls it indirectly as part of some other initialization by running java-home [1], which is a script that decides what JAVA_HOME to use for the engine. This script only runs 'java -version', which imo should not need that much memory. Perhaps there is something else I do not fully understand, such as bacula severely limiting available resources for the process it runs, or something like that. If you only want to debug it, and not as a recommended final solution, you can create a script [2] which only outputs the needed java home. Simply run [1] and make [2] echo the same thing. If [2] exists, [1] will only run it and nothing else, as you can see inside it. I do not think this will work - quite likely engine-backup will fail shortly later, if indeed it gets access to so little memory. Please report back. Thanks and good luck, [1] /usr/share/ovirt-engine/bin/java-home [2] /usr/share/ovirt-engine/bin/java-home.local