djsundog/circuitpython
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

unix/mpthreadport: Use SIGRTMIN+5 instead of SIGUSR1 for thread-GC.

Browse Source 
This changes the signal used to trigger garbage collection from SIGUSR1 to
SIGRTMIN + 5.  SIGUSR1 is quite common compared to SIGRTMIN (measured by
google search results) and is more likely to conflict with libraries that
may use the same signal.

POSIX specifies that there are at least 8 real-time signal so 5 was chosen
as a "random" number to further avoid potential conflict with libraries
that may use SIGRTMIN or SIGRTMAX.

Also, if we ever have a `usignal` module, it would be nice to leave SIGUSR1
and SIGUSR2 free for user programs.
This commit is contained in:
David Lechner 2020-02-15 13:19:58 -06:00 committed by Damien George
parent ce39c958ef
commit 3bd2ae1a36
1 changed files with 5 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
ports/unix/mpthreadport.c
View File

@ -39,6 +39,8 @@
#include <sched.h>
#include <semaphore.h>
#define MP_THREAD_GC_SIGNAL (SIGRTMIN + 5)
// this structure forms a linked list, one node per active thread
typedef struct _thread_t {
pthread_t id; // system id of thread
@ -66,7 +68,7 @@ STATIC sem_t thread_signal_done;
STATIC void mp_thread_gc(int signo, siginfo_t *info, void *context) {
(void)info; // unused
(void)context; // unused
if (signo == SIGUSR1) {
if (signo == MP_THREAD_GC_SIGNAL) {
void gc_collect_regs_and_stack(void);
gc_collect_regs_and_stack();
// We have access to the context (regs, stack) of the thread but it seems
@ -108,7 +110,7 @@ void mp_thread_init(void) {
sa.sa_flags = SA_SIGINFO;
sa.sa_sigaction = mp_thread_gc;
sigemptyset(&sa.sa_mask);
sigaction(SIGUSR1, &sa, NULL);
sigaction(MP_THREAD_GC_SIGNAL, &sa, NULL);
}
void mp_thread_deinit(void) {
@ -144,7 +146,7 @@ void mp_thread_gc_others(void) {
if (!th->ready) {
continue;
}
pthread_kill(th->id, SIGUSR1);
pthread_kill(th->id, MP_THREAD_GC_SIGNAL);
#if defined(__APPLE__)
sem_wait(thread_signal_done_p);
#else