RFR: 8271949: dumppath in -XX:FlightRecorderOptions does not affect

[Denghui Dong]

On Thu, 5 Aug 2021 13:13:12 GMT, Yasumasa Suenaga <ysuenaga at openjdk.org> wrote:

> We set `dumppath` in `-XX:FlightRecorderOptions` or `JFR.configure dumppath` jcmd when we want to set emergency dump path. However they do not afffect.
> 
> ### -XX:FlightRecorderOptions
> 
> 
> $ java -XX:FlightRecorderOptions=dumppath=`pwd` -XX:StartFlightRecording -Xlog:exceptions=info --version
> [0.032s][info][exceptions] Exception <a 'java/lang/IllegalArgumentException'{0x00000007470163b8}: Unknown argument 'dumppath' in diagnostic command.> (0x00000007470163b8)
> thrown [open/src/hotspot/share/services/diagnosticFramework.cpp, line 215]
> for thread 0x00007f4f700236a0
> [0.033s][error][arguments ] Unknown argument 'dumppath' in diagnostic command.
> Error occurred during initialization of VM
> Failure when starting JFR on_create_vm_2
> 
> 
> ### jcmd
> 
> `jcmd` shows the configuration change was succeeded, but it would not affect.
> 
> 
> $ jcmd 1046 JFR.configure dumppath=/tmp
> 1046:
> Dump path: /tmp

src/jdk.jfr/share/classes/jdk/jfr/internal/Options.java line 51:

> 49:     private static final boolean DEFAULT_SAMPLE_THREADS = true;
> 50:     private static final long DEFAULT_MAX_CHUNK_SIZE = 12 * 1024 * 1024;
> 51:     private static final SafePath DEFAULT_DUMP_PATH = new SafePath(".");

Why do need to change DEFAULT_DUMP_PATH here?

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PR: https://git.openjdk.java.net/jdk/pull/5019