sun.java.launcher.pid property usage

[Baesken, Matthias]

Hello,  while looking at some  atoi usages in the codebase I started to wonder about the  "sun.java.launcher.pid"  property.
Currently in java_md_solinux.c  the property is set on Linux only  by default (code is guarded #ifdef __linux__ ).
Later it is passed  to the int  variable _sun_java_launcher_pid (arguments.cpp) and can be retrieved by sun_java_launcher_pid() .
However only in src/hotspot/os/bsd/os_bsd.cpp it is really used.

Is the property still supported (one would need to set it from user side on the command line on non-Linux because it is not set by default on bsd/macOS) ?
Can the coding be removed (or should it enabled for BSD/Mac like we do on Linux) ?

The os_bsd comment mentiones the bug 6351349 :

https://bugs.java.com/bugdatabase/view_bug.do?bug_id=6351349
JDK-6351349 : On linux with the old thread lib, jps should return the same PID as $!

but this looks very old.

Best regards, Matthias




coding parts mentioned :

src/hotspot/os/bsd/os_bsd.cpp
-----------------------------------

void os::init(void) {
  char dummy;   // used to get a guess on initial stack address

  // With BsdThreads the JavaMain thread pid (primordial thread)
  // is different than the pid of the java launcher thread.
  // So, on Bsd, the launcher thread pid is passed to the VM
  // via the sun.java.launcher.pid property.
  // Use this property instead of getpid() if it was correctly passed.
  // See bug 6351349.
  pid_t java_launcher_pid = (pid_t) Arguments::sun_java_launcher_pid();

  _initial_pid = (java_launcher_pid > 0) ? java_launcher_pid : getpid();


arguments.cpp / hpp
---------------------

    if (match_option(option, "-Dsun.java.launcher.pid=", &tail)) {
      _sun_java_launcher_pid = atoi(tail);
      continue;
    }

  static int sun_java_launcher_pid()        { return _sun_java_launcher_pid; }


java_md_solinux.c
---------------------

void SetJavaLauncherPlatformProps() {
   /* Linux only */
#ifdef __linux__
    const char *substr = "-Dsun.java.launcher.pid=";
    char *pid_prop_str = (char *)JLI_MemAlloc(JLI_StrLen(substr) + MAX_PID_STR_SZ + 1);
    sprintf(pid_prop_str, "%s%d", substr, getpid());
    AddOption(pid_prop_str, NULL);
#endif /* __linux__ */
}