My apologies, I'm not sure what part of the networking stack the messages are coming from. It also states: """ could not connect to server: Cannot assign requested address Is the server running on host "<hostname>" and accepting TCP/IP connections on port <port>? """ This error is only printed under a 32-job load, never a single job load.
The processes are indeed connecting over a local network. I have only enabled the logging of connections and disconnections since I figured that would be the most telling :) perhaps that was not the best idea. but, FYI, I see over 5000 such notices in a single minute. I will reconfigure the logging to be more verbose. Thanks, Steve On Tue, Mar 29, 2016 at 4:21 PM Adrian Klaver <adrian.kla...@aklaver.com> wrote: > On 03/29/2016 01:10 PM, Stephen Constable wrote: > > Hi All, > > > > I'm a new-ish sysadmin working on porting legacy scientific code from a > > local server/client to new supercomputer environment. My work is mostly > > done, except that my postgres database doesn't seem to be able to keep > > up with the new environment. The application is written in-house in a > > mixture of FORTAN 77 and C, and uses postgres BLOBS as its main data > > store. This application in particular only reads from the database, it > > never writes, which *should* make it easy to scale. > > > > My main problem is that this client application is unable to connect to > > the database under a modest load (32 simultaneous jobs). The client > > error logs print out messages like "could not connect to server: Cannot > > assign requested address" and "Cannot connect to database [runlog]!!!" > > (an important database of ours). The "cannot assign requested address" > > Well those do not look like Postgres error messages to me, so the first > thing would be to determine what part of the stack is generating them. > > Is the client software connecting to the database over a network? > > Are you using connection pooling? > > > message makes me think it's a configuration issue. The logs are flooded > > with hundreds of connection and disconnection notices per second. This > > Might want to turn off logging connections/disconnections: > > > http://www.postgresql.org/docs/9.4/interactive/runtime-config-logging.html#RUNTIME-CONFIG-LOGGING-WHAT > > log_connections (boolean) > > log_disconnections (boolean) > > > same code and configuration runs fine on our mid-2000's Solaris 10 box > > with postgres 8.4 (albeit very slowly) but totally fails with these > > connection errors on a modern Dell system running CentOS 7 or FreeBSD 10 > > (I tested both) with postgres 9.4. > > > > While the database is under load (and jobs are actively failing), select > > count(*) from pg_stat_activity returns 30-34 ish connections, show > > max_connections returns 100, and show superuser_reserved_connections > > shows 3. My only other hint is that right after a fresh install of > > CentOS 7 my job success rate was around 50%, and now it has approached > > approximately 5%, so something is changing over time. > > > > Does anyone have any advice or experience with similar issues? > > What else does the Postgres log show besides the > connections/disconnections, that might be of interest? > > What does the system log show? > > > > > Thanks, > > Steve > > > > > -- > Adrian Klaver > adrian.kla...@aklaver.com >
