Make TestIndexWriterDelete.testDeleteAllRepeated a monster test and force FSDirectory to prevent OOM.

[dweiss]

Workaround for #14508

[rmuir]

It should not impact jenkins as it is now labelled @Monster.

To try to address @uschindler concerns about disks, we also have @SuppressFsync annotation available in LuceneTestCase, for tests that may need to do tons of commits. real fsyncs are suppressed for a given test class 99% of the time by default, but the annotation can make that 100% of the time.

See logic:

lucene/lucene/test-framework/src/java/org/apache/lucene/tests/util/TestRuleTemporaryFilesCleanup.java

Lines 132 to 137 in ca6879d

	// speed up tests by omitting actual fsync calls to the hardware most of the time.
	if (targetClass.isAnnotationPresent(SuppressFsync.class) || random.nextInt(100) > 0) {
	if (allowed(avoid, DisableFsyncFS.class)) {
	fs = new DisableFsyncFS(fs).getFileSystem(null);
	}
	}

This won't help much if the test truly writes tons of actual data that will get synced in background: in such a situation you need tmpfs or nobarrier, or tone down the test :)

[rmuir]

fwiw: here is my tmpfs setup, which avoids breaking my SSD. This one is 7 years old now. I've got 5MB of trash from lucene builds after 9 days uptime, plenty of trash from other less-behaved programs:

# tmpfs mount with a 3GB limit for /tmp
tmpfs  /tmp  tmpfs  rw,nodev,nosuid,size=3G 0 0

# ~/.gradle/gradle.properties or probably possible via -D or -p or something
# the subdirectory will get created automatically by the build if needed
tests.workDir=/tmp/lucene_gradle