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Re: [Wrapper-user] Many syscalls per second: EAGAIN (Resourcetemporarily unavailable)
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From: Isenberg, H. <ise...@e-...> - 2010-07-27 08:39:09
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It doesn't cause any problems, I'm only wondering if the high frequency of calls per second is normal as we have other problems on that system and I just checked with strace. I thought the wrapper only checks about 1 time per second.
--
Holger Isenberg
e-Spirit AG
> -----Original Message-----
> From: Leif Mortenson [mailto:lei...@ta...]
> Sent: Monday, July 26, 2010 1:05 PM
> To: wra...@li...
> Subject: Re: [Wrapper-user] Many syscalls per second: EAGAIN
> (Resourcetemporarily unavailable)
>
> Holger,
> The Wrapper used to be a single threaded application. Its main loop
> still does non-blocking reads on the pipes and sockets. I believe this
> is what you are seeing.
>
> Is this causing any problems? It is possible to change this logic and
> use more dedicated threads if necessary. I would appreciate your
> input here.
>
> Cheers,
> Leif
>
> On Mon, Jul 26, 2010 at 6:32 PM, Isenberg, Holger
> <ise...@e-...> wrote:
> > Hallo,
> >
> > when monitoring the wrapper process with "strace -p
> Wrapper-PID" on Linux, I'm wondering about the high frequency
> of read() and recvfrom() calls on the pipe and TCP socket
> connection to the Java process and each of them returning
> with "EAGAIN (Resource temporarily unavailable)". The
> frequency is about 10 per second.
> >
> > Is this a bug of strace or does the wrapper calls these
> functions really that fast and why don't they block when
> waiting for data?
> >
> > STATUS | wrapper | 2009/07/10 12:04:50 | --> Wrapper
> Started as Daemon
> > STATUS | wrapper | 2009/07/10 12:04:50 | Java Service
> Wrapper Standard Edition 64-bit 3.3.5
> >
> > Linux [...] 2.6.26-2-amd64 #1 SMP Wed Aug 19 22:33:18 UTC
> 2009 x86_64 GNU/Linux
> >
> > java version "1.6.0_21"
> > Java(TM) SE Runtime Environment (build 1.6.0_21-b06)
> > Java HotSpot(TM) 64-Bit Server VM (build 17.0-b16, mixed mode)
> >
> > gettimeofday({1280134204, 517914}, NULL) = 0
> > read(5, 0x7fff030c5130, 1024) = -1 EAGAIN
> (Resource temporarily unavailable)
> > gettimeofday({1280134204, 518004}, NULL) = 0
> > recvfrom(7, 0x7fff030c554f, 1, 0, 0, 0) = -1 EAGAIN
> (Resource temporarily unavailable)
> > wait4(30121, 0x7fff030c5544, WNOHANG|WSTOPPED, NULL) = 0
> > nanosleep({0, 100000000}, NULL) = 0
> > gettimeofday({1280134204, 618287}, NULL) = 0
> > read(5, 0x7fff030c5130, 1024) = -1 EAGAIN
> (Resource temporarily unavailable)
> > gettimeofday({1280134204, 618392}, NULL) = 0
> > recvfrom(7, 0x7fff030c554f, 1, 0, 0, 0) = -1 EAGAIN
> (Resource temporarily unavailable)
> > wait4(30121, 0x7fff030c5544, WNOHANG|WSTOPPED, NULL) = 0
> > nanosleep({0, 100000000}, NULL) = 0
> > gettimeofday({1280134204, 718729}, NULL) = 0
> > read(5, 0x7fff030c5130, 1024) = -1 EAGAIN
> (Resource temporarily unavailable)
> > gettimeofday({1280134204, 718831}, NULL) = 0
> > recvfrom(7, 0x7fff030c554f, 1, 0, 0, 0) = -1 EAGAIN
> (Resource temporarily unavailable)
> > wait4(30121, 0x7fff030c5544, WNOHANG|WSTOPPED, NULL) = 0
> > nanosleep({0, 100000000}, NULL) = 0
> > gettimeofday({1280134204, 819092}, NULL) = 0
>
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