[PATCH] EnableTracing: output from multiple threads may be mixed together

[云达(Yunda)]

Rickard,

Thanks for the review!

Regards,
Yunda
________________________________________
From: Rickard Bäckman [rickard.backman at oracle.com]
Sent: Thursday, May 02, 2013 13:11
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

Yunda,

the change looks good (not a Reviewer).

/R

On May 2, 2013, at 5:07 AM, 云达(Yunda) wrote:

> Could anyone review this for me, please?
>
> Regards,
> Yunda
>
> From: 云达(Yunda)
> Sent: Friday, April 19, 2013 4:26 PM
> To: hotspot-runtime-dev at openjdk.java.net; serviceability-dev at openjdk.java.net
> Subject: [PATCH] EnableTracing: output from multiple threads may be mixed together
>
> 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(againsthttp://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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