RFR(S): 8153527: break_tty_lock_for_safepoint causes "assert(false) failed: bad tag in log" and broken compile log
vladimir.kozlov at oracle.com
Mon Apr 18 17:30:38 UTC 2016
tty would have the same problem but it use C_HEAP to allocate:
defaultStream::instance = new(ResourceObj::C_HEAP, mtInternal)
Please, look if you can do something similar.
On 4/18/16 4:24 AM, Nils Eliasson wrote:
> 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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