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

On 12/29/2015 02:02 AM, Yedidyah Bar David wrote: > 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 Thanks for the info and response Didi. Doing the above did allow the backup to run successfully.

I had also replaced the Bacula RunScript with "bash -c ulimit" which reported unlimited but I don't play with those types of limits enough to know if that's correctly reporting to what engine-backup is constrained.

I did occur to me that perhaps a better way to learn of any such constraints would be to query Bacula's file daemon (the only necessary Bacula component running on client systems that are getting backed up) since I suspect it must be this component that's actually spawning the RunScript client side. From the Bacula Director (server side) I queried the status of the client which is my oVirt engine and it reports: europa.doubledog.org-fd Version: 5.2.13 (19 February 2013) x86_64-redhat-linux-gnu redhat (Core) Daemon started 28-Dec-15 16:08. Jobs: run=2 running=0. Heap: heap=32,768 smbytes=190,247 max_bytes=1,599,864 bufs=100 max_bufs=6,758 Sizeof: boffset_t=8 size_t=8 debug=0 trace=0 Alas, I know of no way to increase any of the bacula-fd limits. If I dead-end here, perhaps I'll query the Bacula mailing lists.

Meanwhile I tried the following for a more permanent solution but this failed same as before: # diff -u java-home.orig-3.6.1.3 java-home --- java-home.orig-3.6.1.3 2015-12-10 13:07:44.000000000 -0500 +++ java-home 2015-12-30 12:12:45.779462769 -0500 @@ -13,7 +13,7 @@ local ret=1 if [ -x "${dir}/bin/java" ]; then - local version="$("${dir}/bin/java" -version 2>&1 | sed \ + local version="$("${dir}/bin/java" -Xmx 8 -version 2>&1 | sed \ -e 's/^openjdk version "1\.8\.0.*/VERSION_OK/' \ -e 's/^java version "1\.7\.0.*/VERSION_OK/' \ -e 's/^OpenJDK .*(.*).*/VENDOR_OK/' \

If this script is merely checking the validity of the JRE/JDK, should it not be possible to have a test on the rpm details first and only proceed as it does now if that doesn't work? The current tests should work w/o much regard for how the JRE/JDK got installed, but if it was installed via rpm it seems a simpler test could be used as a shortcut.