-Xlog Usage: -Xlog[:[selections][:[output][:[decorators][:output-options]]]]
         where 'selections' are combinations of tags and levels of the form tag1
[+tag2...][*][=level][,...]
         NOTE: Unless wildcard (*) is specified, only log messages tagged with e
xactly the tags specified will be matched.

Available log levels:
 off, trace, debug, info, warning, error

Available log decorators:
 time (t), utctime (utc), uptime (u), timemillis (tm), uptimemillis (um), timena
nos (tn), uptimenanos (un), hostname (hn), pid (p), tid (ti), level (l), tags (t
g)
 Decorators can also be specified as 'none' for no decoration.

Available log tags:
 add, age, alloc, annotation, aot, arguments, attach, barrier, biasedlocking, bl
ocks, bot, breakpoint, bytecode, cds, census, class, classhisto, cleanup, codeca
che, compaction, compilation, constantpool, constraints, container, coops, cpu,
cset, data, datacreation, dcmd, decoder, defaultmethods, director, dump, ergo, e
vent, exceptions, exit, fingerprint, free, freelist, gc, handshake, hashtables,
heap, humongous, ihop, iklass, init, inlining, interpreter, itables, jfr, jit, j
ni, jvmti, liveness, load, loader, logging, malloc, mark, marking, membername, m
emops, metadata, metaspace, methodcomparator, mirror, mmu, module, monitorinflat
ion, monitormismatch, nestmates, nmethod, normalize, objecttagging, obsolete, ol
dobject, oom, oopmap, oops, oopstorage, os, pagesize, parser, patch, path, perf,
 phases, plab, preorder, preview, promotion, protectiondomain, purge, redefine,
ref, refine, region, reloc, remset, resolve, safepoint, sampling, scavenge, sett
ing, smr, stackmap, stacktrace, stackwalk, start, startuptime, state, stats, str
ingdedup, stringtable, subclass, survivor, sweep, system, table, task, thread, t
ime, timer, tlab, tracking, unload, unshareable, update, verification, verify, v
moperation, vmthread, vtables, workgang
 Specifying 'all' instead of a tag combination matches all tag combinations.

Described tag sets:
 logging: Logging for the log framework itself

Available log outputs:
 stdout/stderr
 file=<filename>
  If the filename contains %p and/or %t, they will expand to the JVM's PID and s
tartup timestamp, respectively.
  Additional output-options for file outputs:
   filesize=..  - Target byte size for log rotation (supports K/M/G suffix). If
set to 0, log rotation will not trigger automatically, but can be performed manu
ally (see the VM.log DCMD).
   filecount=.. - Number of files to keep in rotation (not counting the active f
ile). If set to 0, log rotation is disabled. This will cause existing log files
to be overwritten.

Some examples:
 -Xlog
         Log all messages up to 'info' level to stdout with 'uptime', 'levels' a
nd 'tags' decorations.
         (Equivalent to -Xlog:all=info:stdout:uptime,levels,tags).

 -Xlog:gc
         Log messages tagged with 'gc' tag up to 'info' level to stdout, with de
fault decorations.

 -Xlog:gc,safepoint
         Log messages tagged either with 'gc' or 'safepoint' tags, both up to 'i
nfo' level, to stdout, with default decorations.
         (Messages tagged with both 'gc' and 'safepoint' will not be logged.)

 -Xlog:gc+ref=debug
         Log messages tagged with both 'gc' and 'ref' tags, up to 'debug' level,
 to stdout, with default decorations.
         (Messages tagged only with one of the two tags will not be logged.)

 -Xlog:gc=debug:file=gc.txt:none
         Log messages tagged with 'gc' tag up to 'debug' level to file 'gc.txt'
with no decorations.

 -Xlog:gc=trace:file=gctrace.txt:uptimemillis,pids:filecount=5,filesize=1m
         Log messages tagged with 'gc' tag up to 'trace' level to a rotating fil
eset of 5 files of size 1MB,
         using the base name 'gctrace.txt', with 'uptimemillis' and 'pid' decora
tions.

 -Xlog:gc::uptime,tid
         Log messages tagged with 'gc' tag up to 'info' level to output 'stdout'
, using 'uptime' and 'tid' decorations.

 -Xlog:gc*=info,safepoint*=off
         Log messages tagged with at least 'gc' up to 'info' level, but turn off
 logging of messages tagged with 'safepoint'.
         (Messages tagged with both 'gc' and 'safepoint' will not be logged.)

 -Xlog:disable -Xlog:safepoint=trace:safepointtrace.txt
         Turn off all logging, including warnings and errors,
         and then enable messages tagged with 'safepoint' up to 'trace' level to
 file 'safepointtrace.txt'.