Q: Why does tomcat hang after starting on a Linux machine (Redhat 9 etc)? 

A: The most likely cause of such hang is the incompatibility of JRE with the new implementation of
   POSIX library on Red Hat Linux Systems. Multithreading applications like application servers are
   likely to face threading issues when using the new NPTL implementation on Linux.

   To fix this issue, an environment variable LD_ASSUME_KERNEL needs to be exported before starting
   Tomcat. Add the following line to Tomcat's startup.sh script.
   
   export LD_ASSUME_KERNEL=2.4.1 



   Here is what Tomcat's release-notes have to say on Linux:

     Virtual machine crashes can be experienced when using certain combinations of
     kernel / glibc under Linux with Sun Hotspot 1.2 to 1.3. The crashes were
     reported to occur mostly on startup. Sun JDK 1.4 does not exhibit the problems,
     and neither does IBM JDK for Linux.

     The problems can be fixed by reducing the default stack size. At bash shell,
     do "ulimit -s 2048"; use "limit stacksize 2048" for tcsh.

     GLIBC 2.2 / Linux 2.4 users should also define an environment variable:
     export LD_ASSUME_KERNEL=2.2.5

     Additionally, Redhat Linux 9.0 users should use the same setting, to avoid
     stability problems.


     (This problem does exist for JDK 1.4)