I'm currently working on a project porting an application from RedHat
Linux on Intel onto IBM zLinux. Our application requires PostgreSQL at
version 9.n, so the PostgreSQL binaries have been built using the
standard build tools from source. Everything appears run correctly.
However as part of performance testing, our IBM and Linux SysProgs have
been "poking around" using strace and have reported the following (which
they think is an error condition) when hooking up to the postmaster
processes:-
read(3, 0x3ffff875ee0, 16) = -1 EAGAIN (Resource temporarily unavailable)
poll([{fd=3, events=POLLIN}, {fd=6, events=POLLIN}], 2, 200) = 0 (Timeout)
read(3, 0x3ffff875ee0, 16) = -1 EAGAIN (Resource temporarily unavailable)
poll([{fd=3, events=POLLIN}, {fd=6, events=POLLIN}], 2, 10000) = 0 (Timeout)
... repeated many times
From researching the archives, I "believe" the above to be "as
designed" and simply indicates the Postmaster is attempting to read data
from an IP socket which is timing out. Could I ask :-
1. Is this "normal" ?
2. if abnormal, any pointers as to where to start investigating
The reason they latched onto the postmaster process was due to a
perceived high CPU utilisation. For info, we are load testing with 100
connections being accessed from an IBm WebSphere hosted EJB based
application.
Many thanks,
Andrew