GC log is directed to console when starting Solr with Java 11 Open J9 on Windows

This was raised on the mailing list a few months ago: https://lucene.472066.n3.nabble.com/Unrecognized-command-line-option-when-starting-Solr-8-7-with-Java-11-Open-J9-td4470190.html

Running Solr with OOTB options when using Eclipse OpenJ9 "11.0.10"+ you get an error message stating that the -Xlog:gc option is unrecognised, and the GC log is written to the console:

"C:\solr\solr-8.6.2\bin\solr.cmd" start -cloud -p 8888 -s "C:\solr\solr-8.6.2\example\cloud\node1\solr"

JVMJ9VM007W Command-line option unrecognised: -Xlog:gc*:file="C:\solr\solr-8.6.2\example\cloud\node1\solr\..\logs\solr_gc.log":time,uptime:filecount=9,filesize=20M
JVMJ9GC063E Unable to open file '"C' for writing

<?xml version="1.0" ?>

<verbosegc xmlns="http://www.ibm.com/j9/verbosegc" version="741e94ea8_CMPRSS">

<initialized id="1" timestamp="2021-05-17T20:52:49.185">
  <attribute name="gcPolicy" value="-Xgcpolicy:gencon" />
  ...etc...

As pointed out on the mailing list, OpenJ9 changed their handling of -Xlog options in OpenJ9 0.24.0 (January 2021), so that's presumably the first version of OpenJ9 affected by this issue.

The -Xlog:gc:<filename> syntax is replaced with -Xverbosegclog:<updated_filename> according to https://www.eclipse.org/openj9/docs/xlog/

While the bin/solr.cmd has logic for setting -Xverbosegclog when using OpenJ9 ("IBM J9"), that isn't hit because of this conditional block that was added in 2017 https://github.com/apache/solr/commit/86f7d6779a8fee56e4497fde7d8936e916b00814#diff-118de7ae5d9fc032e479321cb4d3ee62ceb68e9f3c845292b44c5e14c0f769cfR1116 which means that all versions >= 9 get the same "GC_LOG_OPTS="-Xlog:gc*:file".

uschindler's comment at the time was that Java 9 is detected before IBM J9. Because IBM J9 for Java 9 will handle the command line options like Oracle which seems like it was true until OpenJ9 0.24.0, but no longer holds for newer versions.

I don't know how many people would be using earlier releases of OpenJ9 on Windows, but I checked jdk-9.0.4+12_openj9-0.9.0 (August 2018) and jdk-11.0.8+10_openj9-0.21.0 (July 2020) and they both started correctly with GC logging using the IBM J9 java options already in the solr.cmd file. So those options seem to work for OpenJ9 in general. Therefore Lisa's suggestion of changing the version check to

if !JAVA_MAJOR_VERSION! GEQ 9 if NOT "%JAVA_VENDOR%" == "IBM J9" (

works and would also allow GC_LOG_OPTS to be set in solr.in.cmd for OpenJ9 users.

Otherwise to use the GC_LOG_OPTS hardcoded in the Java 9+ branch of the solr.cmd, the -XX:+LegacyXlogOption could be used to revert -Xlog in OpenJ9 to its previous behaviour, allowing it to parse -Xlog:gc.

On Linux the bin/solr --the error appears in the solr console log rather than the console itself and but the GC log is still created correctly - which is strange.

JVMJ9VM007W Command-line option unrecognised: -Xlog:gc*:file=/solr/server/logs/8983/solr_gc.log:time,uptime:filecount=9,filesize=20M

I've made a similar change to it to make it use -Xverbosegclog on OpenJ9 too.