Multi-threaded FastCGI servers
Hello,
I'm in the process of modifying a single-threaded FastCGI server. I'm
trying to make the server multi-threaded by using Posix threads and the
FastCGI API's in one of the two ways, as follows:
pcreate_thread(&AcceptThread, 0, (void*)&AcceptThreadFunc, 0);
...
AcceptThreadFunc(...)
{
FCGX_Request FcgiReq;
FCGX_InitRequest(&FcgiReq, 0, 0);
while (FCGX_Accept_r(&FcgiReq) >= 0)
{
// Do the work.
}
}
Or:
FCGX_Request FcgiReq;
FCGX_InitRequest(&FcgiReq, 0, 0);
while (FCGX_Accept_r(&FcgiReq) >= 0)
{
pcreate_thread(&WorkerThread, 0, (void*)&WorkerThreadFunc, 0);
}
...
WorkerThreadFunc(...)
{
// Do the work.
}
I have read that it is possible when using multi-threading in FastCGI
to:
a). Put the entire accept loop into the worker thread, as in the first
code segment (or the threaded.c example), or
b). Have just a single accept loop and put just the code within the
accept loop into a worker thread.
Is this correct? If it is, option b) would imply just a single instance
of an FCGX_Request variable meaning, in turn, that only one FcgiReq.out
would ever be used/accessed by, say, FCGX_FPrintF/PutS. How is this
different from just using FCGI_stdout in a single-threaded FCGI_Accept
loop?
I understand that FCGI_Accept is not thread-safe, whereas FCGI_Accept_r
is, but in option b) the accept loop is outside of the worker thread,
so does it matter which accept API is used? I guess, it might if
FCGI_fwrite, say, is not thread-safe, since that would be used in an
FCGI_Accept loop, but not in a FCGX_Accept_r accept loop...
Basically, is either a) or b) a preferable solution? Is one better in
some circumstances, but not others?
Regards,
Peter Colson.
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