We have been running one of our applications in Red Hat 3 update 5 for some time. Erlang is used as the run-time for the application and is started using mutiple threads. Previously (in Red Hat 3 update 5) when doing a "top", each of the thread activities would be shown:

18105 vsdb 15 0 455M 455M 1028 S 0.4 5.8 3393m 7 beam
18113 vsdb 15 0 455M 455M 1028 S 0.0 5.8 143:55 2 beam
18114 vsdb 15 0 455M 455M 1028 S 0.0 5.8 138:49 4 beam
18115 vsdb 15 0 455M 455M 1028 S 0.0 5.8 127:06 3 beam
18116 vsdb 15 0 455M 455M 1028 S 0.0 5.8 127:31 5 beam

now when doing a top in RedHat 4 update 5, only a single process is shown.

How are the activities on other threads checked? Is this possible?

It looks like the top command got changed. In RHEL 3 you could do a Shift-h to turn off all the threads. This command is not in the RHEL 4 top.