[ruby-core:18444] [PATCH] remove timer signal after last ruby thread has died

Hi -

While playing around with ruby's green threads in ruby 1.8.7 (with 
pthreads disabled) I noticed that after all green threads spawned for a 
ruby process have died, the timer setup to pre-empt the threads is not 
turned off. There is a function for doing this, rb_thread_stop_timer() 
in eval.c, but it is never called after the last ruby green thread has 
died. As a result, even after all threads have joined, the timer 
interrupts continue to fire. The included patch fixes this, and I've 
included some examples to help clarify the behavior I am seeing:

with ruby 1.8.7:

[joe@mawu:/home/joe]% strace -ttT ruby -e 't1 = Thread.new { sleep(10) 
}; t1.join; 10000.times { "aaaaaaaa" * 1000 };'  2>&1 | egrep 
'(sigret|setitimer|timer|exit_group)'
14:29:27.785959 setitimer(ITIMER_VIRTUAL, {it_interval={0, 10000}, 
it_value={0, 10000}}, NULL) = 0 <0.000006>
14:29:37.832131 --- SIGVTALRM (Virtual timer expired) @ 0 (0) ---
14:29:37.832217 rt_sigreturn(0x1a)      = 10127344 <0.000008>
14:29:37.878799 --- SIGVTALRM (Virtual timer expired) @ 0 (0) ---
14:29:37.878867 rt_sigreturn(0x1a)      = 14271352 <0.000009>
14:29:37.945461 --- SIGVTALRM (Virtual timer expired) @ 0 (0) ---
14:29:37.945508 rt_sigreturn(0x1a)      = 7158032 <0.000006>
14:29:37.988797 --- SIGVTALRM (Virtual timer expired) @ 0 (0) ---
14:29:37.988859 rt_sigreturn(0x1a)      = 9634280 <0.000007>
14:29:38.028799 --- SIGVTALRM (Virtual timer expired) @ 0 (0) ---
14:29:38.028855 rt_sigreturn(0x1a)      = 9986760 <0.000006>
14:29:38.075464 --- SIGVTALRM (Virtual timer expired) @ 0 (0) ---
14:29:38.075523 rt_sigreturn(0x1a)      = 11 <0.000005>
14:29:38.148798 --- SIGVTALRM (Virtual timer expired) @ 0 (0) ---
14:29:38.148856 rt_sigreturn(0x1a)      = 11364504 <0.000007>
14:29:38.180574 exit_group(0)           = ?

with the patch applied:

[joe@mawu:/home/joe]% strace -ttT ruby -e 't1 = Thread.new { sleep(10) 
}; t1.join; 10000.times { "aaaaaaaa" * 1000 };'  2>&1 | egrep 
'(sigret|setitimer|timer|exit_group)'
14:29:17.536727 setitimer(ITIMER_VIRTUAL, {it_interval={0, 10000}, 
it_value={0, 10000}}, NULL) = 0 <0.000006>
14:29:27.544435 setitimer(ITIMER_VIRTUAL, {it_interval={0, 0}, 
it_value={0, 0}}, NULL) = 0 <0.000006>
14:29:27.948804 exit_group(0)           = ?


Comments, suggestions, and questions are welcome.

Thanks,
Joe Damato
Aman Gupta