RFR 15: 8217475: Unexpected StackOverflowError in "process reaper" thread

[Roger Riggs]

Please reveiw a change to increase the size of the Process Reaper stack 
for debug builds.
This intermittent issue can be traced to the stack shadow page size 
being larger
in debug builds than in release builds. The problem has only been 
spotted in debug builds.

diff a/src/java.base/share/classes/java/lang/ProcessHandleImpl.java b/src/java.base/share/classes/java/lang/ProcessHandleImpl.java
--- a/src/java.base/share/classes/java/lang/ProcessHandleImpl.java
+++ b/src/java.base/share/classes/java/lang/ProcessHandleImpl.java
@@ -85,12 +85,16 @@
              doPrivileged((PrivilegedAction<Executor>) () -> {
  
                  ThreadGroup tg = Thread.currentThread().getThreadGroup();
                  while (tg.getParent() != null) tg = tg.getParent();
                  ThreadGroup systemThreadGroup = tg;
+
+                // For a debug build, the stack shadow zone is larger;
+                // Increase the total stack size to avoid potential stack overflow.
+                int debugDelta = "release".equals(System.getProperty("jdk.debug")) ? 0 : 8192;
                  final long stackSize = Boolean.getBoolean("jdk.lang.processReaperUseDefaultStackSize")
-                        ? 0 : REAPER_DEFAULT_STACKSIZE;
+                        ? 0 : REAPER_DEFAULT_STACKSIZE + debugDelta;
  
                  ThreadFactory threadFactory = grimReaper -> {
                      Thread t = new Thread(systemThreadGroup, grimReaper,
                              "process reaper", stackSize, false);
                      t.setDaemon(true);

Webrev:
http://cr.openjdk.java.net/~rriggs/webrev-process-stackoverflow-8217475/

Issue:
    https://bugs.openjdk.java.net/browse/JDK-8217475

Thanks, Roger