RFR(S): 8153527: break_tty_lock_for_safepoint causes "assert(false) failed: bad tag in log" and broken compile log
nils.eliasson at oracle.com
Mon Apr 18 11:24:00 UTC 2016
Resizeable is better, but then we assert on expanding the stringbuffer
while being under a different ResourceMark.
On 2016-04-15 19:44, Vladimir Kozlov wrote:
> Use resizable stream:
> stringStream(size_t initial_bufsize = 256);
> 1024 may not be enough.
> On 4/15/16 8:10 AM, Nils Eliasson wrote:
>> Please review this fix of print opto_assembly.
>> The compilelog can get corrupted and the VM may assert on "failed:
>> bad tag in log".
>> When printing assembly in output.cpp we first take the ttylock, print
>> the head and then the method metadata. However the
>> metadata printing makes a vm entry and may block for a safepoint and
>> will then release the lock
>> (break_tty_lock_for_safepoint). After that some of the other compiler
>> thread that haven't safepointed will take the lock
>> and the broken log will be a fact when the safepoint is over and the
>> first thread starts logging again.
>> Print the method metadata to a temporary buffer, then take the tty lock.
>> Repro from bug stops failing.
>> Running :hotspot_all
>> Bug: https://bugs.openjdk.java.net/browse/JDK-8153527
>> Webrev: http://cr.openjdk.java.net/~neliasso/8153527/webrev.01/
>> Nils Eliasson
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