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Re: BUG #3266: SSL broken pipes kill the machine and fill the disk

From: Peter Koczan <pjkoczan(at)gmail(dot)com>
To: Magnus Hagander <magnus(at)hagander(dot)net>
Cc: Bruce Momjian <bruce(at)momjian(dot)us>, pgsql-bugs(at)postgresql(dot)org
Subject: Re: BUG #3266: SSL broken pipes kill the machine and fill the disk
Date: 2007-05-17 22:22:44
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-bugs
Yes, #2829 seems quite similar to my plight. I did take a look through 
the code tree and there appear to be checks for an EINTR status within 
loops in src/backend/libpq/pqcomm.c (line 725 in function pq_recvbuf and 
line 1057 in function internal_flush), that could point to the problem. 
I don't know enough about OpenSSL and it took me a long time to find out 
as much as I did.

FYI, I compiled against OpenSSL 0.9.8d, if that makes any difference.


Magnus Hagander wrote:
> This looks a lot like bug #2829 (excep that one is Windows), as I
> mentioned here:
> Haven't looked into the actual code, though, but Tom had a suggestion in
> the original bug, but AFAIK nobody has done that yet (at least not me.:)
> //Magnus
> Bruce Momjian wrote:
>> I didn't see any comment on this.  Seems like a problem.
>> ---------------------------------------------------------------------------
>> Peter Koczan wrote:
>>> The following bug has been logged online:
>>> Bug reference:      3266
>>> Logged by:          Peter Koczan
>>> Email address:      pjkoczan(at)gmail(dot)com
>>> PostgreSQL version: 8.2.4
>>> Operating system:   CentOS Linux 4.4 (RHEL 4) running on Pentium 4
>>> Description:        SSL broken pipes kill the machine and fill the disk
>>> Details: 
>>> If a connection using SSL is terminated on the client side before a query
>>> completes, postgres keeps trying to write to the broken connection, shooting
>>> CPU and load very high and filling the postgres syslog (I have that pointed
>>> to /var/log/pglog) with ~2000 of the following messages per second.
>>> May 10 14:45:01 mitchell postgres[10340]: [15729-1] LOG:  SSL SYSCALL error:
>>> Broken pipe
>>> This quickly fills up the /var partition on the server.
>>> To replicate the problem:
>>> 1. Connect to an running server using an SSL connection. Using psql is
>>> fine.
>>> 2. Begin a query on any table. For full effect the query should be expensive
>>> and large.
>>> 3. Kill psql *on the client side* BEFORE the query finishes (don't do
>>> anything to the server side connection).
>>> 4. 'tail -f' wherever the postgres server output and error is going to.
>>> 5. Wait a few seconds while the server gets all of its data.
>>> 6. See thousands of error messages fill up your terminal on the server.
>>> This has also happened when people stop web browsers in the middle of
>>> serving up a postgresql-driven web page, but this is harder to replicate.
>>> This usually terminates, but after 3 hours for a query that usually takes 20
>>> seconds. During this time, the server is slow to the point of unusable.
>>> ---------------------------(end of broadcast)---------------------------
>>> TIP 6: explain analyze is your friend

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