100% CPU load

[Stefan (metze) Metzmacher]

Rusty Russell schrieb:
Hi Ronnie,

>> I've found another problem with ctdbd spinning
>> with 100% CPU load reading 0 bytes from the log child.

Here're the fixes for the spinning.

The problem were the dup2() call in the wrong direction, which implicit
closed the stdout.

git pull git://git.samba.org/metze/ctdb/wip.git master-for-ronnie

metze

>>
>> ctdb_log_handler()
>>
>> gets n = 0 from read and log is log_state.
>>
>> I think it's wrong that we don't test for n <= 0 and not error out.
>>
>> I don't understand the code enough to fix it for the log == log_state.
>
> This is connected to stdout and stderr, so it should *never* be closed.
> Hence Ronnie's patch description:
>
> commit bcf494b81f4277dc75f05faccf0c446bd15f6e2b
> Author: Ronnie Sahlberg <ronniesahlberg at gmail.com>
> Date:   Tue Dec 15 19:04:52 2009 +1100
>
>     This is a dodgy patch.
>
>     I saw once where the master ctdbd logging structure was talloc freed
>     which caused issues.
>     So only free the structure if it is NOT the master structure.
>
>     This needs to be looked into in more detail.
>
> I've added a hack to log closing of stdout/stderr, and I don't hit
anything in
> normal running (the parent closes them to set up logging, that's it):
>
> commit 6bcf19397e33cc7e4c63bdd3688003ae3a3add5c
> Author: Rusty Russell <rusty at rustcorp.com.au>
> Date:   Mon Dec 21 15:34:28 2009 +1030
>
>     patch who-is-closing-stderr.patch
>
> diff --git a/lib/replace/replace.c b/lib/replace/replace.c
> index cec158b..3b8dac8 100644
> --- a/lib/replace/replace.c
> +++ b/lib/replace/replace.c
> @@ -621,3 +621,25 @@ int rep_socketpair(int d, int type, int protocol,
int sv[2])
>  	return pipe(sv);
>  }
>  #endif
> +
> +#undef close
> +int _close(int fd)
> +{
> +	if (fd == 0 || fd == 1 || fd == 2) {
> +		static int errorfd = -1;
> +		char msg[100];
> +		if (errorfd == -1) {
> +			int lowfd = open("/tmp/close-errors.log",
> +					 O_WRONLY|O_APPEND|O_CREAT, 0600);
> +			if (lowfd < 0)
> +				abort();
> +			if (dup2(lowfd, 1000) < 0)
> +				abort();
> +			close(lowfd);
> +			errorfd = 1000;
> +		}
> +		sprintf(msg, "Warning: %i closing fd %i!\n", getpid(), fd);
> +		write(errorfd, msg, strlen(msg));
> +	}
> +	return close(fd);
> +}
> diff --git a/lib/replace/replace.h b/lib/replace/replace.h
> index f8a89a7..ad471c4 100644
> --- a/lib/replace/replace.h
> +++ b/lib/replace/replace.h
> @@ -546,4 +546,6 @@ typedef int bool;
>  #define QSORT_CAST (int (*)(const void *, const void *))
>  #endif
>
> +#define close(x) _close(x)
> +
>  #endif /* _LIBREPLACE_REPLACE_H */


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