title: gdb gives me infinite "Program received signal SIGTSTP" when I try to resume
body: <p>I was running vlc in gdb and used ^Z to interrupt it (because ^C was not working) .  After inspecting some stack frames and variables I tried to use "cont" to resume the program, but it kept giving me</p>
  
  <pre><code>Program received signal SIGTSTP, Stopped (user). 
  [Switching to Thread 0x7fffd8d8e700 (LWP 19285)] 
  0x00007ffff700247c in pthread_cond_wait@@GLIBC_2.3.2 ()
      from /lib64/libpthread.so.0
  </code></pre>
  
  <p>Actually, only the first line was the same.  The LWP id cycled between 19285 and 19284, and the address and function alternated as well.</p>
  
  <p>I tried "cont -a" but it says
  `-a' is meaningless in all-stop mode.</p>
  
  <p>What is the proper procedure to resume both threads?</p>