Re: RandomAccessFile and the native futex

It looks like this may have something to do with incompatibility between NPTL threads and Java threads on Fedora Core 4. Anyone run into this problem before? I am using JDK6 with FC4  2.6.12-1.1398_FC4smp. 

A

> Date: Mon, 17 Dec 2007 19:03:42 -0600
> From: [email protected]
> Subject: [ADVANCED-JAVA] RandomAccessFile and the native futex
> To: [email protected]
> 
> Hi All
> 
> I see 52 ms being spent in calls to readFully() method of the RandomAccessFile. I ran strace against my process and figured that these weren't reads going to disk. All reads were being served from the buffer cache (verified by running iostat). It also looks like the 52 ms is a futex timeout but strace doesn't report which system call causes this. I was wondering if anyone has seen this problem before and how do I go about addressing this? Do I have access to the source code of the native library used by RandomAccessFile? Here is the output from strace (the offending line is in bold):
> 
> 
> 29673 16:36:47.747658 
> futex(0x2aac3f62a674, FUTEX_WAIT, 1, {0, 49972000} <unfinished 
> ...>
> 29716 16:36:47.784379 <... futex 
> resumed> ) = -1 ETIMEDOUT (Connection timed out) 
> <0.044427>
> 29716 16:36:47.784469 
> futex(0x2aac3f66e328, FUTEX_WAKE, 1) = 0 
> <0.000012>
> 29716 16:36:47.784548 
> clock_gettime(CLOCK_REALTIME, {1197938207, 784565000}) = 0 
> <0.000012>
> 29716 16:36:47.784610 
> futex(0x2aac3f670314, FUTEX_WAIT, 1, {0, 19970000} <unfinished 
> ...>
> 29673 16:36:47.799354 <... futex 
> resumed> ) = -1 ETIMEDOUT (Connection timed out) 
> <0.051676>
> 29673 16:36:47.799392 
> futex(0x2aac3f2a7228, FUTEX_WAKE, 1) = 0 
> <0.000011>
> 29673 16:36:47.799434 
> clock_gettime(CLOCK_MONOTONIC, {6497274, 522227024}) = 0 
> <0.000007>
> 29673 16:36:47.799481 
> clock_gettime(CLOCK_MONOTONIC, {6497274, 522275024}) = 0 
> <0.000007>
> 
> Thanks
> Avinash
> 
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