Sun Studio code hangs at fork, GCC code runs fine

Question

I am encountering a strange problem where code complied with GCC runs fine, but the same code compiled with Sun Studio 12 compiler hangs at a fork call after an initial set of fork calls.
I'd appreciate your help in solving this.
The code was originally written for GCC, I started using the Sun Studio with a view to using Sun's thread analyzer. I made a couple of changes which I think are inoccuous:
(a) added #ifdef __SUNPRO_CC char * __FUNCTION__ = "name"; #endif
(b) one more #ifdef around one call to ctime_r because the g++ include expects 2 parameters while Sun Studio 12 expects 3 parameters.
The g++ is compiled on a Solaris 9 (1 x sparcv9) using GCC 3.3.3
while the Sun Studio 12 is on a Solaris 10 ( 4 x sparcv9).
Both runs were on the same Solaris 10 machine which has the compiler.
The program is a multi instance socket listener, the main program binds to a socket, then forks off a set of processes which accept connections, those children later fork off other client applications based on the connection data; after those clients exit, the children continue accepting etc. The main program only monitors the child processes, records their status and starts if any of those die.
This is working as expected when compiled with g++.
The exact same code (note the two sets of #ifdefs above) when compiled with Sun PRO CC alway hangs at the second set of fork. That is, it goes through the first set of forks fine, then when a connection is established, it reads the data but hangs right at the fork call.
The application code at this point is:
char * p = pathfind( getenv("PATH"), progname );
if ( !p ) {  printError(); return false; }
pid = fork();
The truss for the Sun Studio code shows
23914: access("/usr/bin/progname", X_OK) = Err#2 ENOENT
23914: access("/usr/you/bin/progname", X_OK) = 0
23914: lwp_park(0x0000000, 0) (sleeping)
while the truss for the g++ code shows
23986: access("/usr/bin/progname", X_OK) = Err#2 ENOENT
23986: access("/usr/you/bin/progname", X_OK) = 0
23996: fork1() = 24005
What am I doing wrong?
Thanks and best regards

Answer 1

If I understand correctly, you are compiling with gcc on Solaris 9, and with Sun Studio on Solaris 10. Since the OS is different, you might be running into OS issues and not compiler issues. What happens if you build with the same gcc version on the Solaris 10 system where you see the problem?
By "OS issues", I mean
1. The program uses unstable or undocumented OS interfaces, or
2. A bug that is new in Solaris 10.
A bug was identified in Solaris 10 that could cause forks to hang. It showed up in the libpkcs11 library as used by the JVM. I don't know whether it showed up elsewhere.
This bug was fixed in Solaris 10u2. If you are using an earlier version of Solaris 10, you could try upgrading.