Request for review: 7173044: Memory monitor demo hangs if MemoryUsage obj returns -1 in getMax

[Sean Chou]

Hi all,

    MemoryMonitor demo will hang if MemoryUsage obj returns -1 in getMax
method.
The demo obtains totalMemory from getMax method, and it is used in
following loop:

"    // .. Memory Free ..
     big.setColor(mfColor);
     int MemUsage = (int) (((totalMemory - usedMemory) / totalMemory) * 10);
     int i = 0;
     for ( ; i < MemUsage ; i++) {
          mfRect.setRect(x1+5,(float) y1+ssH+i*blockHeight,
                    blockWidth, blockHeight-1);
          big.fill(mfRect);
     }
"
   If -1 is returned, MemUsage becomes a very large positive value and the
loop hangs
the demo.

   The bug is not seen in current openjdk because the beans returned all
has a Max
value returned. However, -1 is allowed by spec when Max is not set for the
bean, and
other jdk might return.

   In the patch, max is set to 1m or the max memory usage in history for
the bean
if there is no max specified. Please take a look.

Bug: http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=7173044
Webrev: http://cr.openjdk.java.net/~zhouyx/7173044/webrev.01/  .


-- 
Best Regards,
Sean Chou
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