java.1

.PP
Specifying this option disables automatic use of compressed oops if the
combined result of this and other options influencing the maximum amount
of memory is larger than the range of memory addressable by compressed
oops.
See \f[CB]\-XX:UseCompressedOops\f[R] for further information about
compressed oops.
.PP
Use the option \f[CB]\-XX:MaxRAMPercentage\f[R] instead.
.RE
.TP
.B \f[CB]\-XX:MinRAMFraction=\f[R]\f[I]ratio\f[R]
Sets the maximum amount of memory that the JVM may use for the Java heap
before applying ergonomics heuristics as a fraction of the maximum
amount determined as described in the \f[CB]\-XX:MaxRAM\f[R] option for
small heaps.
A small heap is a heap of approximately 125 MB.
The default value is 2.
.RS
.PP
Use the option \f[CB]\-XX:MinRAMPercentage\f[R] instead.
.RE
.TP
.B \f[CB]\-XX:+UseBiasedLocking\f[R]
Enables the use of biased locking.
Some applications with significant amounts of uncontended
synchronization may attain significant speedups with this flag enabled,
but applications with certain patterns of locking may see slowdowns.
.RS
.PP
By default, this option is disabled.
.RE
.SH OBSOLETE JAVA OPTIONS
.PP
These \f[CB]java\f[R] options are still accepted but ignored, and a
warning is issued when they\[aq]re used.
.TP
.B \f[CB]\-\-illegal\-access=\f[R]\f[I]parameter\f[R]
Controlled \f[I]relaxed strong encapsulation\f[R], as defined in \f[B]JEP
261\f[R]
[https://openjdk.java.net/jeps/261#Relaxed\-strong\-encapsulation].
This option was deprecated in JDK 16 by \f[B]JEP 396\f[R]
[https://openjdk.java.net/jeps/396] and made obsolete in JDK 17 by
\f[B]JEP 403\f[R] [https://openjdk.java.net/jeps/403].
.RS
.RE
.SH REMOVED JAVA OPTIONS
.PP
These \f[CB]java\f[R] options have been removed in JDK 17 and using them
results in an error of:
.RS
.PP
\f[CB]Unrecognized\ VM\ option\f[R] \f[I]option\-name\f[R]
.RE
.TP
.B \f[CB]\-XX:+UseMembar\f[R]
Enabled issuing membars on thread\-state transitions.
This option was disabled by default on all platforms except ARM servers,
where it was enabled.
.RS
.RE
.TP
.B \f[CB]\-XX:MaxPermSize=\f[R]\f[I]size\f[R]
Sets the maximum permanent generation space size (in bytes).
This option was deprecated in JDK 8 and superseded by the
\f[CB]\-XX:MaxMetaspaceSize\f[R] option.
.RS
.RE
.TP
.B \f[CB]\-XX:PermSize=\f[R]\f[I]size\f[R]
Sets the space (in bytes) allocated to the permanent generation that
triggers a garbage collection if it\[aq]s exceeded.
This option was deprecated in JDK 8 and superseded by the
\f[CB]\-XX:MetaspaceSize\f[R] option.
.RS
.RE
.TP
.B \f[CB]\-XX:+TraceClassLoading\f[R]
Enables tracing of classes as they are loaded.
By default, this option is disabled and classes aren\[aq]t traced.
.RS
.PP
The replacement Unified Logging syntax is
\f[CB]\-Xlog:class+load=\f[R]\f[I]level\f[R].
See \f[B]Enable Logging with the JVM Unified Logging Framework\f[R]
.PP
Use \f[I]level\f[R]=\f[CB]info\f[R] for regular information, or
\f[I]level\f[R]=\f[CB]debug\f[R] for additional information.
In Unified Logging syntax, \f[CB]\-verbose:class\f[R] equals
\f[CB]\-Xlog:class+load=info,class+unload=info\f[R].
.RE
.TP
.B \f[CB]\-XX:+TraceClassLoadingPreorder\f[R]
Enables tracing of all loaded classes in the order in which they\[aq]re
referenced.
By default, this option is disabled and classes aren\[aq]t traced.
.RS
.PP
The replacement Unified Logging syntax is
\f[CB]\-Xlog:class+preorder=debug\f[R].
See \f[B]Enable Logging with the JVM Unified Logging Framework\f[R].
.RE
.TP
.B \f[CB]\-XX:+TraceClassResolution\f[R]
Enables tracing of constant pool resolutions.
By default, this option is disabled and constant pool resolutions
aren\[aq]t traced.
.RS
.PP
The replacement Unified Logging syntax is
\f[CB]\-Xlog:class+resolve=debug\f[R].
See \f[B]Enable Logging with the JVM Unified Logging Framework\f[R].
.RE
.TP
.B \f[CB]\-XX:+TraceLoaderConstraints\f[R]
Enables tracing of the loader constraints recording.
By default, this option is disabled and loader constraints recording
isn\[aq]t traced.
.RS
.PP
The replacement Unified Logging syntax is
\f[CB]\-Xlog:class+loader+constraints=info\f[R].
See \f[B]Enable Logging with the JVM Unified Logging Framework\f[R].
.RE
.PP
For the lists and descriptions of options removed in previous releases
see the \f[I]Removed Java Options\f[R] section in:
.IP \[bu] 2
\f[B]Java Platform, Standard Edition Tools Reference, Release 16\f[R]
[https://docs.oracle.com/en/java/javase/16/docs/specs/man/java.html]
.IP \[bu] 2
\f[B]Java Platform, Standard Edition Tools Reference, Release 15\f[R]
[https://docs.oracle.com/en/java/javase/15/docs/specs/man/java.html]
.IP \[bu] 2
\f[B]Java Platform, Standard Edition Tools Reference, Release 14\f[R]
[https://docs.oracle.com/en/java/javase/14/docs/specs/man/java.html]
.IP \[bu] 2
\f[B]Java Platform, Standard Edition Tools Reference, Release 13\f[R]
[https://docs.oracle.com/en/java/javase/13/docs/specs/man/java.html]
.IP \[bu] 2
\f[B]Java Platform, Standard Edition Tools Reference, Release 12\f[R]
[https://docs.oracle.com/en/java/javase/12/tools/java.html#GUID\-3B1CE181\-CD30\-4178\-9602\-230B800D4FAE]
.IP \[bu] 2
\f[B]Java Platform, Standard Edition Tools Reference, Release 11\f[R]
[https://docs.oracle.com/en/java/javase/11/tools/java.html#GUID\-741FC470\-AA3E\-494A\-8D2B\-1B1FE4A990D1]
.IP \[bu] 2
\f[B]Java Platform, Standard Edition Tools Reference, Release 10\f[R]
[https://docs.oracle.com/javase/10/tools/java.htm#JSWOR624]
.IP \[bu] 2
\f[B]Java Platform, Standard Edition Tools Reference, Release 9\f[R]
[https://docs.oracle.com/javase/9/tools/java.htm#JSWOR624]
.IP \[bu] 2
\f[B]Java Platform, Standard Edition Tools Reference, Release 8 for
Oracle JDK on Windows\f[R]
[https://docs.oracle.com/javase/8/docs/technotes/tools/windows/java.html#BGBCIEFC]
.IP \[bu] 2
\f[B]Java Platform, Standard Edition Tools Reference, Release 8 for
Oracle JDK on Solaris, Linux, and macOS\f[R]
[https://docs.oracle.com/javase/8/docs/technotes/tools/unix/java.html#BGBCIEFC]
.SH JAVA COMMAND\-LINE ARGUMENT FILES
.PP
You can shorten or simplify the \f[CB]java\f[R] command by using
\f[CB]\@\f[R] argument files to specify one or more text files that
contain arguments, such as options and class names, which are passed to
the \f[CB]java\f[R] command.
This let\[aq]s you to create \f[CB]java\f[R] commands of any length on any
operating system.
.PP
In the command line, use the at sign (\f[CB]\@\f[R]) prefix to identify an
argument file that contains \f[CB]java\f[R] options and class names.
When the \f[CB]java\f[R] command encounters a file beginning with the at
sign (\f[CB]\@\f[R]), it expands the contents of that file into an
argument list just as they would be specified on the command line.
.PP
The \f[CB]java\f[R] launcher expands the argument file contents until it
encounters the \f[CB]\-\-disable\-\@files\f[R] option.
You can use the \f[CB]\-\-disable\-\@files\f[R] option anywhere on the
command line, including in an argument file, to stop \f[CB]\@\f[R]
argument files expansion.
.PP
The following items describe the syntax of \f[CB]java\f[R] argument files:
.IP \[bu] 2
The argument file must contain only ASCII characters or characters in
system default encoding that\[aq]s ASCII friendly, such as UTF\-8.
.IP \[bu] 2
The argument file size must not exceed MAXINT (2,147,483,647) bytes.
.IP \[bu] 2
The launcher doesn\[aq]t expand wildcards that are present within an
argument file.
.IP \[bu] 2
Use white space or new line characters to separate arguments included in
the file.
.IP \[bu] 2
White space includes a white space character, \f[CB]\\t\f[R],
\f[CB]\\n\f[R], \f[CB]\\r\f[R], and \f[CB]\\f\f[R].
.RS 2
.PP
For example, it is possible to have a path with a space, such as
\f[CB]c:\\Program\ Files\f[R] that can be specified as either
\f[CB]"c:\\\\Program\ Files"\f[R] or, to avoid an escape,
\f[CB]c:\\Program"\ "Files\f[R].
.RE
.IP \[bu] 2
Any option that contains spaces, such as a path component, must be
within quotation marks using quotation (\[aq]"\[aq]) characters in its
entirety.
.IP \[bu] 2
A string within quotation marks may contain the characters \f[CB]\\n\f[R],
\f[CB]\\r\f[R], \f[CB]\\t\f[R], and \f[CB]\\f\f[R].
They are converted to their respective ASCII codes.
.IP \[bu] 2
If a file name contains embedded spaces, then put the whole file name in
double quotation marks.
.IP \[bu] 2
File names in an argument file are relative to the current directory,
not to the location of the argument file.
.IP \[bu] 2
Use the number sign \f[CB]#\f[R] in the argument file to identify
comments.
All characters following the \f[CB]#\f[R] are ignored until the end of
line.
.IP \[bu] 2
Additional at sign \f[CB]\@\f[R] prefixes to \f[CB]\@\f[R] prefixed options
act as an escape, (the first \f[CB]\@\f[R] is removed and the rest of the
arguments are presented to the launcher literally).
.IP \[bu] 2
Lines may be continued using the continuation character (\f[CB]\\\f[R]) at
the end\-of\-line.
The two lines are concatenated with the leading white spaces trimmed.
To prevent trimming the leading white spaces, a continuation character
(\f[CB]\\\f[R]) may be placed at the first column.
.IP \[bu] 2
Because backslash (\\) is an escape character, a backslash character
must be escaped with another backslash character.
.IP \[bu] 2
Partial quote is allowed and is closed by an end\-of\-file.
.IP \[bu] 2
An open quote stops at end\-of\-line unless \f[CB]\\\f[R] is the last
character, which then joins the next line by removing all leading white
space characters.
.IP \[bu] 2
Wildcards (*) aren\[aq]t allowed in these lists (such as specifying
\f[CB]*.java\f[R]).
.IP \[bu] 2
Use of the at sign (\f[CB]\@\f[R]) to recursively interpret files
isn\[aq]t supported.
.SS Example of Open or Partial Quotes in an Argument File
.PP
In the argument file,
.IP
.nf
\f[CB]
\-cp\ "lib/
cool/
app/
jars
\f[R]
.fi
.PP
this is interpreted as:
.RS
.PP
\f[CB]\-cp\ lib/cool/app/jars\f[R]
.RE
.SS Example of a Backslash Character Escaped with Another Backslash
Character in an Argument File
.PP
To output the following:
.RS
.PP
\f[CB]\-cp\ c:\\Program\ Files\ (x86)\\Java\\jre\\lib\\ext;c:\\Program\ Files\\Java\\jre9\\lib\\ext\f[R]
.RE
.PP
The backslash character must be specified in the argument file as:
.RS
.PP
\f[CB]\-cp\ "c:\\\\Program\ Files\ (x86)\\\\Java\\\\jre\\\\lib\\\\ext;c:\\\\Program\ Files\\\\Java\\\\jre9\\\\lib\\\\ext"\f[R]
.RE
.SS Example of an EOL Escape Used to Force Concatenation of Lines in an
Argument File
.PP
In the argument file,
.IP
.nf
\f[CB]
\-cp\ "/lib/cool\ app/jars:\\
\ \ \ \ /lib/another\ app/jars"
\f[R]
.fi
.PP
This is interpreted as:
.RS
.PP
\f[CB]\-cp\ /lib/cool\ app/jars:/lib/another\ app/jars\f[R]
.RE
.SS Example of Line Continuation with Leading Spaces in an Argument File
.PP
In the argument file,
.IP
.nf
\f[CB]
\-cp\ "/lib/cool\\
\\app/jars???
\f[R]
.fi
.PP
This is interpreted as:
.PP
\f[CB]\-cp\ /lib/cool\ app/jars\f[R]
.SS Examples of Using Single Argument File
.PP
You can use a single argument file, such as \f[CB]myargumentfile\f[R] in
the following example, to hold all required \f[CB]java\f[R] arguments:
.RS
.PP
\f[CB]java\ \@myargumentfile\f[R]
.RE
.SS Examples of Using Argument Files with Paths
.PP
You can include relative paths in argument files; however, they\[aq]re
relative to the current working directory and not to the paths of the
argument files themselves.
In the following example, \f[CB]path1/options\f[R] and
\f[CB]path2/options\f[R] represent argument files with different paths.
Any relative paths that they contain are relative to the current working
directory and not to the argument files:
.RS
.PP
\f[CB]java\ \@path1/options\ \@path2/classes\f[R]
.RE
.SH CODE HEAP STATE ANALYTICS
.SS Overview
.PP
There are occasions when having insight into the current state of the
JVM code heap would be helpful to answer questions such as:
.IP \[bu] 2
Why was the JIT turned off and then on again and again?
.IP \[bu] 2
Where has all the code heap space gone?
.IP \[bu] 2
Why is the method sweeper not working effectively?
.PP
To provide this insight, a code heap state analytics feature has been
implemented that enables on\-the\-fly analysis of the code heap.
The analytics process is divided into two parts.
The first part examines the entire code heap and aggregates all
information that is believed to be useful or important.
The second part consists of several independent steps that print the
collected information with an emphasis on different aspects of the data.
Data collection and printing are done on an "on request" basis.
.SS Syntax
.PP
Requests for real\-time, on\-the\-fly analysis can be issued with the
following command:
.RS
.PP
\f[CB]jcmd\f[R] \f[I]pid\f[R] \f[CB]Compiler.CodeHeap_Analytics\f[R]
[\f[I]function\f[R]] [\f[I]granularity\f[R]]
.RE
.PP
If you are only interested in how the code heap looks like after running
a sample workload, you can use the command line option:
.RS
.PP
\f[CB]\-Xlog:codecache=Trace\f[R]
.RE
.PP
To see the code heap state when a "CodeCache full" condition exists,
start the VM with the command line option:
.RS
.PP
\f[CB]\-Xlog:codecache=Debug\f[R]
.RE
.PP
See \f[B]CodeHeap State Analytics (OpenJDK)\f[R]
[https://bugs.openjdk.java.net/secure/attachment/75649/JVM_CodeHeap_StateAnalytics_V2.pdf]
for a detailed description of the code heap state analytics feature, the
supported functions, and the granularity options.
.SH ENABLE LOGGING WITH THE JVM UNIFIED LOGGING FRAMEWORK
.PP
You use the \f[CB]\-Xlog\f[R] option to configure or enable logging with
the Java Virtual Machine (JVM) unified logging framework.
.SS Synopsis
.RS
.PP
\f[CB]\-Xlog\f[R][\f[CB]:\f[R][\f[I]what\f[R]][\f[CB]:\f[R][\f[I]output\f[R]][\f[CB]:\f[R][\f[I]decorators\f[R]][\f[CB]:\f[R]\f[I]output\-options\f[R][\f[CB],\f[R]...]]]]]
.PP
\f[CB]\-Xlog:\f[R]\f[I]directive\f[R]
.RE
.TP
.B \f[I]what\f[R]
Specifies a combination of tags and levels of the form
\f[I]tag1\f[R][\f[CB]+\f[R]\f[I]tag2\f[R]...][\f[CB]*\f[R]][\f[CB]=\f[R]\f[I]level\f[R]][\f[CB],\f[R]...].
Unless the wildcard (\f[CB]*\f[R]) is specified, only log messages tagged
with exactly the tags specified are matched.
See \f[B]\-Xlog Tags and Levels\f[R].
.RS
.RE
.TP
.B \f[I]output\f[R]
Sets the type of output.
Omitting the \f[I]output\f[R] type defaults to \f[CB]stdout\f[R].
See \f[B]\-Xlog Output\f[R].
.RS
.RE
.TP
.B \f[I]decorators\f[R]
Configures the output to use a custom set of decorators.
Omitting \f[I]decorators\f[R] defaults to \f[CB]uptime\f[R],
\f[CB]level\f[R], and \f[CB]tags\f[R].
See \f[B]Decorations\f[R].
.RS
.RE
.TP
.B \f[I]output\-options\f[R]
Sets the \f[CB]\-Xlog\f[R] logging output options.
.RS
.RE
.TP
.B \f[I]directive\f[R]
A global option or subcommand: help, disable, async
.RS
.RE
.SS Description
.PP
The Java Virtual Machine (JVM) unified logging framework provides a
common logging system for all components of the JVM.
GC logging for the JVM has been changed to use the new logging
framework.
The mapping of old GC flags to the corresponding new Xlog configuration
is described in \f[B]Convert GC Logging Flags to Xlog\f[R].
In addition, runtime logging has also been changed to use the JVM
unified logging framework.
The mapping of legacy runtime logging flags to the corresponding new
Xlog configuration is described in \f[B]Convert Runtime Logging Flags to
Xlog\f[R].
.PP
The following provides quick reference to the \f[CB]\-Xlog\f[R] command
and syntax for options:
.TP
.B \f[CB]\-Xlog\f[R]
Enables JVM logging on an \f[CB]info\f[R] level.
.RS
.RE
.TP
.B \f[CB]\-Xlog:help\f[R]
Prints \f[CB]\-Xlog\f[R] usage syntax and available tags, levels, and
decorators along with example command lines with explanations.
.RS
.RE
.TP
.B \f[CB]\-Xlog:disable\f[R]
Turns off all logging and clears all configuration of the logging
framework including the default configuration for warnings and errors.
.RS
.RE
.TP
.B \f[CB]\-Xlog\f[R][\f[CB]:\f[R]\f[I]option\f[R]]
Applies multiple arguments in the order that they appear on the command
line.
Multiple \f[CB]\-Xlog\f[R] arguments for the same output override each
other in their given order.
.RS
.PP
The \f[I]option\f[R] is set as:
.RS
.PP
[\f[I]tag\-selection\f[R]][\f[CB]:\f[R][\f[I]output\f[R]][\f[CB]:\f[R][\f[I]decorators\f[R]][\f[CB]:\f[R]\f[I]output\-options\f[R]]]]
.RE
.PP
Omitting the \f[I]tag\-selection\f[R] defaults to a tag\-set of
\f[CB]all\f[R] and a level of \f[CB]info\f[R].
.RS
.PP
\f[I]tag\f[R][\f[CB]+\f[R]...] \f[CB]all\f[R]
.RE
.PP
The \f[CB]all\f[R] tag is a meta tag consisting of all tag\-sets
available.
The asterisk \f[CB]*\f[R] in a tag set definition denotes a wildcard tag
match.
Matching with a wildcard selects all tag sets that contain \f[I]at
least\f[R] the specified tags.
Without the wildcard, only exact matches of the specified tag sets are
selected.
.PP
\f[I]output\-options\f[R] is
.RS
.PP
\f[CB]filecount=\f[R]\f[I]file\-count\f[R] \f[CB]filesize=\f[R]\f[I]file size
with optional K, M or G suffix\f[R]
.RE
.RE
.SS Default Configuration
.PP
When the \f[CB]\-Xlog\f[R] option and nothing else is specified on the
command line, the default configuration is used.
The default configuration logs all messages with a level that matches
either warning or error regardless of what tags the message is
associated with.
The default configuration is equivalent to entering the following on the
command line:
.RS
.PP
\f[CB]\-Xlog:all=warning:stdout:uptime,level,tags\f[R]
.RE
.SS Controlling Logging at Runtime
.PP
Logging can also be controlled at run time through Diagnostic Commands
(with the \f[B]jcmd\f[R] utility).
Everything that can be specified on the command line can also be
specified dynamically with the \f[CB]VM.log\f[R] command.
As the diagnostic commands are automatically exposed as MBeans, you can
use JMX to change logging configuration at run time.
.SS \-Xlog Tags and Levels
.PP
Each log message has a level and a tag set associated with it.
The level of the message corresponds to its details, and the tag set
corresponds to what the message contains or which JVM component it
involves (such as, \f[CB]gc\f[R], \f[CB]jit\f[R], or \f[CB]os\f[R]).
Mapping GC flags to the Xlog configuration is described in \f[B]Convert
GC Logging Flags to Xlog\f[R].
Mapping legacy runtime logging flags to the corresponding Xlog
configuration is described in \f[B]Convert Runtime Logging Flags to
Xlog\f[R].
.PP
\f[B]Available log levels:\f[R]
.IP \[bu] 2
\f[CB]off\f[R]
.IP \[bu] 2
\f[CB]trace\f[R]
.IP \[bu] 2
\f[CB]debug\f[R]
.IP \[bu] 2
\f[CB]info\f[R]
.IP \[bu] 2
\f[CB]warning\f[R]
.IP \[bu] 2
\f[CB]error\f[R]
.PP
\f[B]Available log tags:\f[R]
.PP
There are literally dozens of log tags, which in the right combinations,
will enable a range of logging output.
The full set of available log tags can be seen using
\f[CB]\-Xlog:help\f[R].
Specifying \f[CB]all\f[R] instead of a tag combination matches all tag
combinations.
.SS \-Xlog Output
.PP
The \f[CB]\-Xlog\f[R] option supports the following types of outputs:
.IP \[bu] 2
\f[CB]stdout\f[R] \-\-\- Sends output to stdout
.IP \[bu] 2
\f[CB]stderr\f[R] \-\-\- Sends output to stderr
.IP \[bu] 2
\f[CB]file=\f[R]\f[I]filename\f[R] \-\-\- Sends output to text file(s).
.PP
When using \f[CB]file=\f[R]\f[I]filename\f[R], specifying \f[CB]%p\f[R]
and/or \f[CB]%t\f[R] in the file name expands to the JVM\[aq]s PID and
startup timestamp, respectively.
You can also configure text files to handle file rotation based on file
size and a number of files to rotate.
For example, to rotate the log file every 10 MB and keep 5 files in
rotation, specify the options \f[CB]filesize=10M,\ filecount=5\f[R].
The target size of the files isn\[aq]t guaranteed to be exact, it\[aq]s
just an approximate value.
Files are rotated by default with up to 5 rotated files of target size
20 MB, unless configured otherwise.
Specifying \f[CB]filecount=0\f[R] means that the log file shouldn\[aq]t be
rotated.
There\[aq]s a possibility of the pre\-existing log file getting
overwritten.
.SS \-Xlog Output Mode
.PP
By default logging messages are output synchronously \- each log message
is written to the designated output when the logging call is made.
But you can instead use asynchronous logging mode by specifying:
.TP
.B \f[CB]\-Xlog:async\f[R]
Write all logging asynchronously.
.RS
.RE
.PP
In asynchronous logging mode, log sites enqueue all logging messages to
an intermediate buffer and a standalone thread is responsible for
flushing them to the corresponding outputs.
The intermediate buffer is bounded and on buffer exhaustion the
enqueuing message is discarded.
Log entry write operations are guaranteed non\-blocking.
.PP
The option \f[CB]\-XX:AsyncLogBufferSize=N\f[R] specifies the memory
budget in bytes for the intermediate buffer.
The default value should be big enough to cater for most cases.
Users can provide a custom value to trade memory overhead for log
accuracy if they need to.
.SS Decorations
.PP
Logging messages are decorated with information about the message.
You can configure each output to use a custom set of decorators.
The order of the output is always the same as listed in the table.
You can configure the decorations to be used at run time.
Decorations are prepended to the log message.
For example:
.IP
.nf
\f[CB]
[6.567s][info][gc,old]\ Old\ collection\ complete
\f[R]
.fi
.PP
Omitting \f[CB]decorators\f[R] defaults to \f[CB]uptime\f[R],
\f[CB]level\f[R], and \f[CB]tags\f[R].
The \f[CB]none\f[R] decorator is special and is used to turn off all
decorations.
.PP
\f[CB]time\f[R] (\f[CB]t\f[R]), \f[CB]utctime\f[R] (\f[CB]utc\f[R]),
\f[CB]uptime\f[R] (\f[CB]u\f[R]), \f[CB]timemillis\f[R] (\f[CB]tm\f[R]),
\f[CB]uptimemillis\f[R] (\f[CB]um\f[R]), \f[CB]timenanos\f[R] (\f[CB]tn\f[R]),
\f[CB]uptimenanos\f[R] (\f[CB]un\f[R]), \f[CB]hostname\f[R] (\f[CB]hn\f[R]),
\f[CB]pid\f[R] (\f[CB]p\f[R]), \f[CB]tid\f[R] (\f[CB]ti\f[R]), \f[CB]level\f[R]
(\f[CB]l\f[R]), \f[CB]tags\f[R] (\f[CB]tg\f[R]) decorators can also be
specified as \f[CB]none\f[R] for no decoration.
.PP
.TS
tab(@);
lw(14.9n) lw(55.1n).
T{
Decorations
T}@T{
Description
T}
_
T{
\f[CB]time\f[R] or \f[CB]t\f[R]
T}@T{
Current time and date in ISO\-8601 format.
T}
T{
\f[CB]utctime\f[R] or \f[CB]utc\f[R]
T}@T{
Universal Time Coordinated or Coordinated Universal Time.
T}
T{
\f[CB]uptime\f[R] or \f[CB]u\f[R]
T}@T{
Time since the start of the JVM in seconds and milliseconds.
For example, 6.567s.
T}
T{
\f[CB]timemillis\f[R] or \f[CB]tm\f[R]
T}@T{
The same value as generated by \f[CB]System.currentTimeMillis()\f[R]
T}
T{
\f[CB]uptimemillis\f[R] or \f[CB]um\f[R]
T}@T{
Milliseconds since the JVM started.
T}
T{
\f[CB]timenanos\f[R] or \f[CB]tn\f[R]
T}@T{
The same value generated by \f[CB]System.nanoTime()\f[R].
T}
T{
\f[CB]uptimenanos\f[R] or \f[CB]un\f[R]
T}@T{
Nanoseconds since the JVM started.
T}
T{
\f[CB]hostname\f[R] or \f[CB]hn\f[R]
T}@T{
The host name.
T}
T{
\f[CB]pid\f[R] or \f[CB]p\f[R]
T}@T{
The process identifier.
T}
T{
\f[CB]tid\f[R] or \f[CB]ti\f[R]
T}@T{
The thread identifier.
T}
T{
\f[CB]level\f[R] or \f[CB]l\f[R]
T}@T{
The level associated with the log message.
T}
T{
\f[CB]tags\f[R] or \f[CB]tg\f[R]
T}@T{
The tag\-set associated with the log message.
T}
.TE
.SS Convert GC Logging Flags to Xlog
.PP
.TS
tab(@);
lw(22.4n) lw(16.5n) lw(31.2n).
T{
Legacy Garbage Collection (GC) Flag
T}@T{
Xlog Configuration
T}@T{
Comment
T}
_
T{
\f[CB]G1PrintHeapRegions\f[R]
T}@T{
\f[CB]\-Xlog:gc+region=trace\f[R]
T}@T{
Not Applicable
T}
T{
\f[CB]GCLogFileSize\f[R]
T}@T{
No configuration available
T}@T{
Log rotation is handled by the framework.
T}
T{
\f[CB]NumberOfGCLogFiles\f[R]
T}@T{
Not Applicable
T}@T{
Log rotation is handled by the framework.
T}
T{
\f[CB]PrintAdaptiveSizePolicy\f[R]
T}@T{
\f[CB]\-Xlog:gc+ergo*=\f[R]\f[I]level\f[R]
T}@T{
Use a \f[I]level\f[R] of \f[CB]debug\f[R] for most of the information, or a
\f[I]level\f[R] of \f[CB]trace\f[R] for all of what was logged for
\f[CB]PrintAdaptiveSizePolicy\f[R].
T}
T{
\f[CB]PrintGC\f[R]
T}@T{
\f[CB]\-Xlog:gc\f[R]
T}@T{
Not Applicable
T}
T{
\f[CB]PrintGCApplicationConcurrentTime\f[R]
T}@T{
\f[CB]\-Xlog:safepoint\f[R]
T}@T{
Note that \f[CB]PrintGCApplicationConcurrentTime\f[R] and
\f[CB]PrintGCApplicationStoppedTime\f[R] are logged on the same tag and
aren\[aq]t separated in the new logging.
T}
T{
\f[CB]PrintGCApplicationStoppedTime\f[R]
T}@T{
\f[CB]\-Xlog:safepoint\f[R]
T}@T{
Note that \f[CB]PrintGCApplicationConcurrentTime\f[R] and
\f[CB]PrintGCApplicationStoppedTime\f[R] are logged on the same tag and
not separated in the new logging.
T}
T{
\f[CB]PrintGCCause\f[R]
T}@T{
Not Applicable
T}@T{
GC cause is now always logged.
T}
T{
\f[CB]PrintGCDateStamps\f[R]
T}@T{
Not Applicable
T}@T{
Date stamps are logged by the framework.
T}
T{
\f[CB]PrintGCDetails\f[R]
T}@T{
\f[CB]\-Xlog:gc*\f[R]
T}@T{
Not Applicable
T}
T{
\f[CB]PrintGCID\f[R]
T}@T{
Not Applicable
T}@T{
GC ID is now always logged.
T}
T{
\f[CB]PrintGCTaskTimeStamps\f[R]
T}@T{
\f[CB]\-Xlog:gc+task*=debug\f[R]
T}@T{
Not Applicable
T}
T{
\f[CB]PrintGCTimeStamps\f[R]
T}@T{
Not Applicable
T}@T{
Time stamps are logged by the framework.
T}
T{
\f[CB]PrintHeapAtGC\f[R]
T}@T{
\f[CB]\-Xlog:gc+heap=trace\f[R]
T}@T{
Not Applicable
T}
T{
\f[CB]PrintReferenceGC\f[R]
T}@T{
\f[CB]\-Xlog:gc+ref*=debug\f[R]
T}@T{
Note that in the old logging, \f[CB]PrintReferenceGC\f[R] had an effect
only if \f[CB]PrintGCDetails\f[R] was also enabled.
T}
T{
\f[CB]PrintStringDeduplicationStatistics\f[R]
T}@T{
`\-Xlog:gc+stringdedup*=debug
T}@T{
` Not Applicable
T}
T{
\f[CB]PrintTenuringDistribution\f[R]
T}@T{
\f[CB]\-Xlog:gc+age*=\f[R]\f[I]level\f[R]
T}@T{
Use a \f[I]level\f[R] of \f[CB]debug\f[R] for the most relevant
information, or a \f[I]level\f[R] of \f[CB]trace\f[R] for all of what was
logged for \f[CB]PrintTenuringDistribution\f[R].
T}
T{
\f[CB]UseGCLogFileRotation\f[R]
T}@T{
Not Applicable
T}@T{
What was logged for \f[CB]PrintTenuringDistribution\f[R].
T}
.TE
.SS Convert Runtime Logging Flags to Xlog
.PP
These legacy flags are no longer recognized and will cause an error if
used directly.
Use their unified logging equivalent instead.
.PP
.TS
tab(@);
lw(15.0n) lw(20.2n) lw(34.7n).
T{
Legacy Runtime Flag
T}@T{
Xlog Configuration
T}@T{
Comment
T}
_
T{
\f[CB]TraceExceptions\f[R]
T}@T{
\f[CB]\-Xlog:exceptions=info\f[R]
T}@T{
Not Applicable
T}
T{
\f[CB]TraceClassLoading\f[R]
T}@T{
\f[CB]\-Xlog:class+load=\f[R]\f[I]level\f[R]
T}@T{
Use \f[I]level\f[R]=\f[CB]info\f[R] for regular information, or
\f[I]level\f[R]=\f[CB]debug\f[R] for additional information.
In Unified Logging syntax, \f[CB]\-verbose:class\f[R] equals
\f[CB]\-Xlog:class+load=info,class+unload=info\f[R].
T}
T{
\f[CB]TraceClassLoadingPreorder\f[R]
T}@T{
\f[CB]\-Xlog:class+preorder=debug\f[R]
T}@T{
Not Applicable
T}
T{
\f[CB]TraceClassUnloading\f[R]
T}@T{
\f[CB]\-Xlog:class+unload=\f[R]\f[I]level\f[R]
T}@T{
Use \f[I]level\f[R]=\f[CB]info\f[R] for regular information, or
\f[I]level\f[R]=\f[CB]trace\f[R] for additional information.
In Unified Logging syntax, \f[CB]\-verbose:class\f[R] equals
\f[CB]\-Xlog:class+load=info,class+unload=info\f[R].
T}
T{
\f[CB]VerboseVerification\f[R]
T}@T{
\f[CB]\-Xlog:verification=info\f[R]
T}@T{
Not Applicable
T}
T{
\f[CB]TraceClassPaths\f[R]
T}@T{
\f[CB]\-Xlog:class+path=info\f[R]
T}@T{
Not Applicable
T}
T{
\f[CB]TraceClassResolution\f[R]
T}@T{
\f[CB]\-Xlog:class+resolve=debug\f[R]
T}@T{
Not Applicable
T}
T{
\f[CB]TraceClassInitialization\f[R]
T}@T{
\f[CB]\-Xlog:class+init=info\f[R]
T}@T{
Not Applicable
T}
T{
\f[CB]TraceLoaderConstraints\f[R]
T}@T{
\f[CB]\-Xlog:class+loader+constraints=info\f[R]
T}@T{
Not Applicable
T}
T{
\f[CB]TraceClassLoaderData\f[R]
T}@T{
\f[CB]\-Xlog:class+loader+data=\f[R]\f[I]level\f[R]
T}@T{
Use \f[I]level\f[R]=\f[CB]debug\f[R] for regular information or
\f[I]level\f[R]=\f[CB]trace\f[R] for additional information.
T}
T{
\f[CB]TraceSafepointCleanupTime\f[R]
T}@T{
\f[CB]\-Xlog:safepoint+cleanup=info\f[R]
T}@T{
Not Applicable
T}
T{
\f[CB]TraceSafepoint\f[R]
T}@T{
\f[CB]\-Xlog:safepoint=debug\f[R]
T}@T{
Not Applicable
T}
T{
\f[CB]TraceMonitorInflation\f[R]
T}@T{
\f[CB]\-Xlog:monitorinflation=debug\f[R]
T}@T{
Not Applicable
T}
T{
\f[CB]TraceBiasedLocking\f[R]
T}@T{
\f[CB]\-Xlog:biasedlocking=\f[R]\f[I]level\f[R]
T}@T{
Use \f[I]level\f[R]=\f[CB]info\f[R] for regular information, or
\f[I]level\f[R]=\f[CB]trace\f[R] for additional information.
T}
T{
\f[CB]TraceRedefineClasses\f[R]
T}@T{
\f[CB]\-Xlog:redefine+class*=\f[R]\f[I]level\f[R]
T}@T{
\f[I]level\f[R]=\f[CB]info\f[R], \f[CB]debug\f[R], and \f[CB]trace\f[R] provide
increasing amounts of information.
T}
.TE
.SS \-Xlog Usage Examples
.PP
The following are \f[CB]\-Xlog\f[R] examples.
.TP
.B \f[CB]\-Xlog\f[R]
Logs all messages by using the \f[CB]info\f[R] level to \f[CB]stdout\f[R]
with \f[CB]uptime\f[R], \f[CB]levels\f[R], and \f[CB]tags\f[R] decorations.
This is equivalent to using:
.RS
.RS
.PP
\f[CB]\-Xlog:all=info:stdout:uptime,levels,tags\f[R]
.RE
.RE
.TP
.B \f[CB]\-Xlog:gc\f[R]
Logs messages tagged with the \f[CB]gc\f[R] tag using \f[CB]info\f[R] level
to \f[CB]stdout\f[R].
The default configuration for all other messages at level
\f[CB]warning\f[R] is in effect.
.RS
.RE
.TP
.B \f[CB]\-Xlog:gc,safepoint\f[R]