Reported by Felix Yang, felix.yang@huawei.com.

          The upstream patch set parameter use_vfork_if_available to true when call os::fork_and_exec in VM_ReportJavaOutOfMemory::doit().
          But looks like the 8u backport did something inconsistent: the change was not made in the correct place.
          The 8u backport patch: http://hg.openjdk.java.net/jdk8u/jdk8u/hotspot/rev/97d605522fcb

        Patch for jdk8u-dev:

        diff -r 775e2bf92114 src/share/vm/utilities/vmError.cpp
        --- a/src/share/vm/utilities/vmError.cpp Wed Aug 07 17:00:19 2019 +0800
        +++ b/src/share/vm/utilities/vmError.cpp Fri Nov 15 14:23:50 2019 +0800
        @@ -1060,7 +1060,7 @@
               out.print_raw (cmd);
               out.print_raw_cr("\" ...");

        - if (os::fork_and_exec(cmd, true) < 0) {
        + if (os::fork_and_exec(cmd) < 0) {
                 out.print_cr("os::fork_and_exec failed: %s (%d)", strerror(errno), errno);
               }
             }
        @@ -1147,7 +1147,7 @@
        #endif
             tty->print_cr("\"%s\"...", cmd);

        - if (os::fork_and_exec(cmd) < 0) {
        + if (os::fork_and_exec(cmd, true) < 0) {
               tty->print_cr("os::fork_and_exec failed: %s (%d)", strerror(errno), errno);
             }
           }