|The PostgreSQL 9.0 Reference Manual - Volume 2 - Programming Guide
by The PostgreSQL Global Development Group
Paperback (6"x9"), 478 pages
RRP £14.95 ($19.95)
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1.18 Behavior in Threaded Programs
libpq is reentrant and thread-safe by default.
You might need to use special compiler command-line
options when you compile your application code. Refer to your
system's documentation for information about how to build
thread-enabled applications, or look in
PTHREAD_LIBS. This function allows the querying of
libpq's thread-safe status:
Returns the thread safety status of the
int PQisthreadsafe();Returns 1 if the libpq is thread-safe and 0 if it is not.
One thread restriction is that no two threads attempt to manipulate
PGconn object at the same time. In particular,
you cannot issue concurrent commands from different threads through
the same connection object. (If you need to run concurrent commands,
use multiple connections.)
PGresult objects are read-only after creation, and so
can be passed around freely between threads.
The deprecated functions
PQoidStatus are not thread-safe and should not be
used in multithread programs.
can be replaced by
PQoidStatus can be replaced by
If you are using Kerberos inside your application (in addition to inside
libpq), you will need to do locking around
Kerberos calls because Kerberos functions are not thread-safe. See
PQregisterThreadLock in the
libpq source code for a way to do cooperative
locking between libpq and your application.
If you experience problems with threaded applications, run the program in ‘src/tools/thread’ to see if your platform has thread-unsafe functions. This program is run by ‘configure’, but for binary distributions your library might not match the library used to build the binaries.
|ISBN 9781906966065||The PostgreSQL 9.0 Reference Manual - Volume 2 - Programming Guide||See the print edition|