Linux Threads


Linux threads are like multiple processes that share the same virtual memory.  They even have different PIDs, and appear multiple times in 'ps' and 'top' output.

  PID USER SIZE  RSS SHARE STAT %CPU %MEM   TIME COMMAND
 7185 bri  1488 1488  1412 S     0.0  0.5   0:00 stunnel
 7186 bri  1488 1488  1412 S     0.0  0.5   0:00 stunnel
 7187 bri  1488 1488  1412 S     0.0  0.5   0:00 stunnel
 7188 bri  1488 1488  1412 S     0.0  0.5   0:00 stunnel
 7189 bri  1488 1488  1412 S     0.0  0.5   0:00 stunnel

Threads need to be ultra careful to not affect each other in undesired ways.  Locking mechanisms are used to cooperate when accessing data that may be in use by other threads.