Dear mailing list,
the following issue has occurred when embedding CHICKEN 5.4.0 in a
multithreaded C program. I have reproduced the issue on macOS and
NetBSD 10. Either I am doing something wrong or this is a bug.
The program I am embedding just returns the squared input.
;; x.scm
(import (chicken platform) (chicken foreign))
(define-external (bar (int i)) int
(* i i))
(return-to-host)
The C program starts one extra thread and then both threads
call the exported function bar. To ensure no concurrency issues
occur, I have protected the calls to bar with a pthread mutex.
// y.c
#include <chicken.h>
#include <pthread.h>
#include <stdio.h>
#include <unistd.h>
extern int bar(int);
static pthread_mutex_t m = PTHREAD_MUTEX_INITIALIZER;
static int call(void) {
pthread_mutex_lock(&m);
int r = bar(1);
pthread_mutex_unlock(&m);
return r;
}
static void *run(void *_) {
printf("value: %d\n", call());
sleep(1);
printf("value: %d\n", call());
return 0;
}
int main(void) {
CHICKEN_run(C_toplevel);
pthread_t t;
pthread_create(&t, 0, run, 0);
run(0);
pthread_join(t, 0);
return 0;
}
To build and run the test case, I used:
csc -e -o test x.scm y.c
./test
>From CHICKEN's documentation, I had the impression that this
interface usage should be supported. Am I doing something silly?
Can anybody reproduce this issue on other systems?
Last comment: I have started this with gdb and one thread does
not leave C_save_and_reclaim, IIRC. I keeps calling some
mark_* and C_reclaim functions. My libchicken does not have
symbols, so I couldn't look in more details what is happening,
but it looks like the thread never leaves the function. That
only happens if I call the interface with two or more threads.
-Diogo
