[PATCH] EnableTracing: output from multiple threads may be mixed together
Rickard Bäckman
rickard.backman at oracle.com
Thu May 9 01:52:34 PDT 2013
Looks good to me!
/R
On May 9, 2013, at 8:38 AM, 云达(Yunda) wrote:
> Rickard,
>
> Actually I've considered the option and I just thought it's less elegant. But just as you said, it's clearer and easier to read. The updated and tested change:
>
> diff -r 627cf9e9ea31 src/share/vm/runtime/globals.hpp
> --- a/src/share/vm/runtime/globals.hpp Mon May 06 10:29:49 2013 -0700
> +++ b/src/share/vm/runtime/globals.hpp Thu May 09 14:36:35 2013 +0800
> @@ -3634,7 +3634,10 @@
> "Include GC cause in GC logging") \
> \
> product(bool, EnableTracing, false, \
> - "Enable event-based tracing")
> + "Enable event-based tracing") \
> + \
> + product(bool, UseLockedTracing, false, \
> + "Use locked-tracing when doing event-based tracing")
>
> /*
> * Macros for factoring of globals
> diff -r 627cf9e9ea31 src/share/vm/trace/traceEventClasses.xsl
> --- a/src/share/vm/trace/traceEventClasses.xsl Mon May 06 10:29:49 2013 -0700
> +++ b/src/share/vm/trace/traceEventClasses.xsl Thu May 09 14:36:35 2013 +0800
> @@ -132,6 +132,15 @@
> void writeEvent(void) {
> ResourceMark rm;
> HandleMark hm;
> + if (UseLockedTracing) {
> + ttyLocker lock;
> + writeEventContent();
> + } else {
> + writeEventContent();
> + }
> + }
> +
> + void writeEventContent() {
> TraceStream ts(*tty);
> ts.print("<xsl:value-of select="@label"/>: [");
> <xsl:apply-templates select="value|structvalue" mode="write-data"/>
>
>
> Regards,
> Yunda
>
>> -----Original Message-----
>> From: Rickard Bäckman [mailto:rickard.backman at oracle.com]
>> Sent: Wednesday, May 08, 2013 3:03 PM
>> To: David Holmes
>> Cc: 云达(Yunda); serviceability-dev at openjdk.java.net;
>> hotspot-runtime-dev at openjdk.java.net
>> Subject: Re: [PATCH] EnableTracing: output from multiple threads may be mixed
>> together
>>
>> One option could be to move the content of writeEvent() to its own method
>> (maybe writeEventContent()) and just do
>>
>> if (UseLockedTracing) {
>> ttyLocker lock;
>> writeEventContent();
>> } else {
>> writeEventContent();
>> }
>>
>> I think it makes it easier to read.
>>
>> /R
>>
>> On May 8, 2013, at 2:41 AM, David Holmes wrote:
>>
>>> On 7/05/2013 10:33 PM, 云达(Yunda) wrote:
>>>> David,
>>>>
>>>> Sorry about the stupid mistake. And please see the tested change below.
>> Since I don't find an elegant way to define a ttyLocker object, I use the static
>> methods of ttyLocker instead.
>>>
>>> Yeah there's no elegant solution when you need to conditionalize
>>> things. :(
>>>
>>> This looks fine to me but the serviceability folk should chime back in.
>>>
>>> Thanks,
>>> David
>>>
>>>> diff -r 627cf9e9ea31 src/share/vm/runtime/globals.hpp
>>>> --- a/src/share/vm/runtime/globals.hpp Mon May 06 10:29:49 2013
>>>> -0700
>>>> +++ b/src/share/vm/runtime/globals.hpp Tue May 07 20:04:24 2013
>>>> +++ +0800
>>>> @@ -3634,7 +3634,10 @@
>>>> "Include GC cause in GC logging")
>> \
>>>>
>> \
>>>> product(bool, EnableTracing, false,
>> \
>>>> - "Enable event-based tracing")
>>>> + "Enable event-based tracing")
>> \
>>>> +
>> \
>>>> + product(bool, UseLockedTracing, false,
>> \
>>>> + "Use locked-tracing when doing event-based
>>>> + tracing")
>>>>
>>>> /*
>>>> * Macros for factoring of globals
>>>> diff -r 627cf9e9ea31 src/share/vm/trace/traceEventClasses.xsl
>>>> --- a/src/share/vm/trace/traceEventClasses.xsl Mon May 06 10:29:49
>>>> 2013 -0700
>>>> +++ b/src/share/vm/trace/traceEventClasses.xsl Tue May 07 20:04:24
>>>> +++ 2013 +0800
>>>> @@ -132,10 +132,17 @@
>>>> void writeEvent(void) {
>>>> ResourceMark rm;
>>>> HandleMark hm;
>>>> + int holder;
>>>> + if (UseLockedTracing) {
>>>> + holder = ttyLocker::hold_tty();
>>>> + }
>>>> TraceStream ts(*tty);
>>>> ts.print("<xsl:value-of select="@label"/>: [");
>>>> <xsl:apply-templates select="value|structvalue" mode="write-data"/>
>>>> ts.print("]\n");
>>>> + if (UseLockedTracing) {
>>>> + ttyLocker::release_tty(holder);
>>>> + }
>>>> }
>>>> };
>>>>
>>>>
>>>> Regards,
>>>> Yunda
>>>>
>>>>
>>>>> -----Original Message-----
>>>>> From: David Holmes [mailto:david.holmes at oracle.com]
>>>>> Sent: Tuesday, May 07, 2013 5:50 PM
>>>>> To: 云达(Yunda)
>>>>> Cc: hotspot-runtime-dev at openjdk.java.net;
>>>>> serviceability-dev at openjdk.java.net
>>>>> Subject: Re: [PATCH] EnableTracing: output from multiple threads may
>>>>> be mixed together
>>>>>
>>>>> On 7/05/2013 7:43 PM, 云达(Yunda) wrote:
>>>>>> Hi David,
>>>>>>
>>>>>> Thanks for the review and I see your concern. Please see the
>>>>>> updated change
>>>>> below:
>>>>>>
>>>>>> diff -r 627cf9e9ea31 src/share/vm/runtime/globals.hpp
>>>>>> --- a/src/share/vm/runtime/globals.hpp Mon May 06 10:29:49 2013
>>>>>> -0700
>>>>>> +++ b/src/share/vm/runtime/globals.hpp Tue May 07 17:38:58 2013
>>>>>> +++ +0800
>>>>>> @@ -3634,7 +3634,10 @@
>>>>>> "Include GC cause in GC logging")
>>>>> \
>>>>>>
>>>>> \
>>>>>> product(bool, EnableTracing, false,
>>>>> \
>>>>>> - "Enable event-based tracing")
>>>>>> + "Enable event-based tracing")
>>>>> \
>>>>>> +
>>>>> \
>>>>>> + product(bool, UseLockedTracing, false,
>>>>> \
>>>>>> + "Use locked-tracing when doing event-based
>>>>>> + tracing")
>>>>>>
>>>>>> /*
>>>>>> * Macros for factoring of globals diff -r 627cf9e9ea31
>>>>>> src/share/vm/trace/traceEventClasses.xsl
>>>>>> --- a/src/share/vm/trace/traceEventClasses.xsl Mon May 06 10:29:49
>>>>>> 2013 -0700
>>>>>> +++ b/src/share/vm/trace/traceEventClasses.xsl Tue May 07 17:38:58
>>>>>> +++ 2013 +0800
>>>>>> @@ -132,6 +132,9 @@
>>>>>> void writeEvent(void) {
>>>>>> ResourceMark rm;
>>>>>> HandleMark hm;
>>>>>> + if (UseLockedTracing) {
>>>>>> + ttyLocker ttyl;
>>>>>> + }
>>>>>
>>>>> Ah that doesn't work - the ttyLocker is block-scoped by the if
>>>>> statement so it will be created, grab the lock, then immediately be
>>>>> destructed and the lock released.
>>>>>
>>>>> David
>>>>> -----
>>>>>
>>>>>> TraceStream ts(*tty);
>>>>>> ts.print("<xsl:value-of select="@label"/>: [");
>>>>>> <xsl:apply-templates select="value|structvalue"
>>>>>> mode="write-data"/>
>>>>>>
>>>>>> Regards,
>>>>>> Yunda
>>>>>>
>>>>>>> -----Original Message-----
>>>>>>> From: David Holmes [mailto:david.holmes at oracle.com]
>>>>>>> Sent: Tuesday, May 07, 2013 10:39 AM
>>>>>>> To: 云达(Yunda)
>>>>>>> Cc: hotspot-runtime-dev at openjdk.java.net;
>>>>>>> serviceability-dev at openjdk.java.net
>>>>>>> Subject: Re: [PATCH] EnableTracing: output from multiple threads
>>>>>>> may be mixed together
>>>>>>>
>>>>>>> Hi Yunda,
>>>>>>>
>>>>>>> There is a potential problem with using a ttyLocker here,
>>>>>>> depending on exactly what events are being traced and from where -
>>>>>>> you must always be in code where it is both safe to acquire the
>>>>>>> lock, and safe to block waiting for the lock if it is not available.
>>>>>>>
>>>>>>> I think I would prefer to see unlocked tracing by default with a
>>>>>>> flag to use locked-tracing if requested.
>>>>>>>
>>>>>>> David
>>>>>>>
>>>>>>> On 19/04/2013 6:26 PM, 云达(Yunda) wrote:
>>>>>>>> Hi all,
>>>>>>>>
>>>>>>>> I found that the output from multiple threads may be mixed
>>>>>>>> together when using EnableTracing. It happens many times in my test
>> case like this:
>>>>>>>>
>>>>>>>> Allocation outside TLAB: [Allocation in new TLAB: [Allocation in
>>>>>>>> new
>>>>>>>> TLAB: [Allocation in new TLAB: [Class = [C, Allocation in new TLAB:
>>>>>>>> [Class = [I, Allocation in new TLAB: [Java Monitor Wait: [Class =
>>>>>>>> java/lang/String, Allocation Size = 24, Allocation Size = 24,
>>>>>>>> Class = java/lang/String, Class = [I, Allocation in new TLAB:
>>>>>>>> [Class = [C, Allocation in new TLAB: [Allocation Size = 192]
>>>>>>>>
>>>>>>>> Class =
>>>>>>>> com/sun/org/apache/xerces/internal/dom/DeferredElementNSImpl,
>>>>>>>> Allocation Size = 24, Allocation Size = 24, TLAB Size = 23712280]
>>>>>>>>
>>>>>>>> TLAB Size = 24607080]
>>>>>>>>
>>>>>>>> Allocation Size = 24, Monitor Class =
>>>>>>>> java/lang/ref/Reference$Lock, TLAB Size = 25054480]
>>>>>>>>
>>>>>>>> TLAB Size = 25054480]
>>>>>>>>
>>>>>>>> Allocation in new TLAB: [Class = [CTLAB Size = 24607080]
>>>>>>>>
>>>>>>>> Allocation Size = 72, Class = [C, TLAB Size = 24159728]
>>>>>>>>
>>>>>>>> , Allocation Size = 32, TLAB Size = 23712288]
>>>>>>>>
>>>>>>>> It's very confusing and it's even not easy to tell how many
>>>>>>>> events there are. I think the reason is that the writeEvent()
>>>>>>>> method of each
>>>>>>>> Event* class output the fields of event one by one without using
>>>>>>>> any lock. So I made a small patch which add ttyLocker to
>>>>>>>> writeEvent() method and after applying this patch there's no
>>>>>>>> output mixed together in my test case(against
>>>>> http://hg.openjdk.java.net/hsx/hsx24/hotspot/):
>>>>>>>>
>>>>>>>> diff -r edd1619a3ae4 src/share/vm/trace/traceEventClasses.xsl
>>>>>>>>
>>>>>>>> --- a/src/share/vm/trace/traceEventClasses.xsl Thu Apr 18
>> 13:50:58
>>>>>>>> 2013 -0700
>>>>>>>>
>>>>>>>> +++ b/src/share/vm/trace/traceEventClasses.xsl Fri Apr 19
>>>>>>>> +++ 16:12:38
>>>>>>>> +++ 2013
>>>>>>>> +0800
>>>>>>>>
>>>>>>>> @@ -132,6 +132,7 @@
>>>>>>>>
>>>>>>>> void writeEvent(void) {
>>>>>>>>
>>>>>>>> ResourceMark rm;
>>>>>>>>
>>>>>>>> HandleMark hm;
>>>>>>>>
>>>>>>>> + ttyLocker ttyl;
>>>>>>>>
>>>>>>>> TraceStream ts(*tty);
>>>>>>>>
>>>>>>>> ts.print("<xsl:value-of select="@label"/>: [");
>>>>>>>>
>>>>>>>> <xsl:apply-templates select="value|structvalue"
>>>>>>>> mode="write-data"/>
>>>>>>>>
>>>>>>>> I searched before sending this mail I didn't find anyone who
>>>>>>>> covering thisJ
>>>>>>>>
>>>>>>>> Regards,
>>>>>>>>
>>>>>>>> Yunda
>>>>>>>>
>>>>>>>>
>>>>>>>> -----------------------------------------------------------------
>>>>>>>> ---
>>>>>>>> --
>>>>>>>> --
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>
>
> ________________________________
>
> This email (including any attachments) is confidential and may be legally privileged. If you received this email in error, please delete it immediately and do not copy it or use it for any purpose or disclose its contents to any other person. Thank you.
>
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