Tcl Source Code

Creating threads from C and then creating a Tcl interpreter in those threads, then destroying the Tcl interpreter and then destroying the thread leaks memory.  

Simple demo attached.   This eventually exhausts all RAM on the system despite not creating many concurrent interpreters.

You should probably create the thread via Tcl_CreateThread() as shown in your updated program below. For me, this does not appear to leak.

-gustaf


============================================================================
#include <stdatomic.h>
#include <pthread.h>
#include <unistd.h>
#include <stdio.h>
#include <time.h>
#include <tcl.h>

_Atomic unsigned long long threadCount = 0;
_Atomic unsigned long long interpCount = 0;

static Tcl_ThreadCreateProc threadRunner;
static Tcl_ThreadCreateType threadRunner(ClientData clientData) {
	Tcl_Interp *interp;
	int tclReturnValue;

	threadCount++;

	interp = Tcl_CreateInterp();

	interpCount++;

	tclReturnValue = Tcl_Init(interp);
	if (tclReturnValue != TCL_OK) {
		fprintf(stderr, "warning: TclInit() failed.\n");
	}

	Tcl_DeleteInterp(interp);

	interpCount--;

	Tcl_FinalizeThread();

	threadCount--;
}

int main(int argc, char **argv) {
	Tcl_ThreadId threadId;
	struct timespec sleepTime;
	int pthreadCreateRet;
	int idx = 0;
	int tclMajor, tclMinor, tclPatchLevel;

	Tcl_FindExecutable(argv[0]);

	Tcl_GetVersion(&tclMajor, &tclMinor, &tclPatchLevel, NULL);

	printf("Testing Tcl version %i.%i.%i\n", tclMajor, tclMinor, tclPatchLevel);

	for (idx = 0;; idx++) {
		if ((idx % 1024) == 0) {
			idx = 0;

			printf("Thread Count: %llu, Interp Count: %llu\n", threadCount, interpCount);
		}

		pthreadCreateRet = Tcl_CreateThread(&threadId, threadRunner, NULL, TCL_THREAD_STACK_DEFAULT, TCL_THREAD_NOFLAGS);

		if (pthreadCreateRet != 0) {
			fprintf(stderr, "error: pthread_create() failed, exiting.\n");

			return(1);
		}

		sleepTime.tv_sec = 0;
		sleepTime.tv_nsec = 1000000;
		nanosleep(&sleepTime, NULL);
	}

	return(0);
}

I have not tried it from tclsh since it wouldn't be relevant to my problem -- I'm creating threads from C and I cannot change that.

Sorry (input eaten, thick fingers)))

So again: no, I cannot reproduce this leak (currently still have not tried your code, but neither in tclsh with thread 2.7 module, nor within my multithreaded apps)...

Have you tried my example with tclsh?

What ?

> I can reproduce a leak with our thread module and from my multithreaded apps (don't tried your code)...

So you can reproduce this leak ?

I can reproduce a leak with our thread module and from my multithreaded apps (don't tried your code)...

Possibly, you have something wrong in your c-code (resp. you miss something that does Tcl_AppInit, Tcl_Main, other subsystems resp. some events in Tcl_init, etc.)...

For example did you still have a leak, if you will create a new thread with "Tcl_CreateThread" instead of "pthread_create"?

Second, simply test it using thread module, just from your tclsh like here:

load thread27
time { puts [time { thread::create {thread::release} } 1000] } 10

As already said, I see no leak at all, if I do that with current 8.5, 8.6 and 8.7 (trunk)...

No change with Tcl 8.6.5.

I did update the source to print the version number (via Tcl_GetVersion()), exit early if pthread_create() fails, and call Tcl_FindExecutable(argv[0]) -- updated source attached.



++ x86_64-generic-linux-gnu-gcc -std=gnu11 -o test-leak test-leak.c -Wall -pthread -ltcl8.6 -I./tcl8.6.5/INST/include -L./tcl8.6.5/INST/lib -Wl,-R,/home/rkeene/devel/appfs/build/tcl8.6.5/INST/lib '-DPACKAGE_NAME="tcl"' '-DPACKAGE_TARNAME="tcl"' '-DPACKAGE_VERSION="8.6"' '-DPACKAGE_STRING="tcl 8.6"' '-DPACKAGE_BUGREPORT=""' -DSTDC_HEADERS=1 -DHAVE_SYS_TYPES_H=1 -DHAVE_SYS_STAT_H=1 -DHAVE_STDLIB_H=1 -DHAVE_STRING_H=1 -DHAVE_MEMORY_H=1 -DHAVE_STRINGS_H=1 -DHAVE_INTTYPES_H=1 -DHAVE_STDINT_H=1 -DHAVE_UNISTD_H=1 -DHAVE_SYS_PARAM_H=1 -DUSE_THREAD_ALLOC=1 -D_REENTRANT=1 -D_THREAD_SAFE=1 -DHAVE_PTHREAD_ATTR_SETSTACKSIZE=1 -DHAVE_PTHREAD_ATFORK=1 -DTCL_THREADS=1 '-DTCL_CFGVAL_ENCODING="iso8859-1"' -DHAVE_ZLIB=1 '-DMODULE_SCOPE=extern __attribute__((__visibility__("hidden")))' -DHAVE_HIDDEN=1 -DHAVE_CAST_TO_UNION=1 '-DTCL_SHLIB_EXT=".so"' -DNDEBUG=1 -DTCL_CFG_OPTIMIZED=1 -DTCL_TOMMATH=1 -DMP_PREC=4 -D_LARGEFILE64_SOURCE=1 -DTCL_WIDE_INT_IS_LONG=1 -DHAVE_GETCWD=1 -DHAVE_MKSTEMP=1 -DHAVE_OPENDIR=1 -DHAVE_STRTOL=1 -DHAVE_WAITPID=1 -DHAVE_GETNAMEINFO=1 -DHAVE_GETADDRINFO=1 -DHAVE_FREEADDRINFO=1 -DHAVE_GAI_STRERROR=1 -DHAVE_STRUCT_ADDRINFO=1 -DHAVE_STRUCT_IN6_ADDR=1 -DHAVE_STRUCT_SOCKADDR_IN6=1 -DHAVE_STRUCT_SOCKADDR_STORAGE=1 -DHAVE_GETPWUID_R_5=1 -DHAVE_GETPWUID_R=1 -DHAVE_GETPWNAM_R_5=1 -DHAVE_GETPWNAM_R=1 -DHAVE_GETGRGID_R_5=1 -DHAVE_GETGRGID_R=1 -DHAVE_GETGRNAM_R_5=1 -DHAVE_GETGRNAM_R=1 -DHAVE_GETHOSTBYNAME_R_6=1 -DHAVE_GETHOSTBYNAME_R=1 -DHAVE_GETHOSTBYADDR_R_8=1 -DHAVE_GETHOSTBYADDR_R=1 -DHAVE_TERMIOS_H=1 -DHAVE_SYS_IOCTL_H=1 -DHAVE_SYS_TIME_H=1 -DTIME_WITH_SYS_TIME=1 -DHAVE_GMTIME_R=1 -DHAVE_LOCALTIME_R=1 -DHAVE_MKTIME=1 -DHAVE_TM_GMTOFF=1 -DHAVE_TIMEZONE_VAR=1 -DHAVE_STRUCT_STAT_ST_BLOCKS=1 -DHAVE_STRUCT_STAT_ST_BLKSIZE=1 -DHAVE_BLKCNT_T=1 -DHAVE_INTPTR_T=1 -DHAVE_UINTPTR_T=1 -DHAVE_SIGNED_CHAR=1 -DHAVE_LANGINFO=1 -DHAVE_MKSTEMPS=1 -DHAVE_FTS=1 -DHAVE_SYS_IOCTL_H=1 -DTCL_UNLOAD_DLLS=1 -DHAVE_CPUID=1
Testing Tcl version 8.6.5
Thread Count: 0, Interp Count: 0
Thread Count: 1, Interp Count: 1
Thread Count: 0, Interp Count: 0
Thread Count: 1, Interp Count: 1
Thread Count: 0, Interp Count: 0
Thread Count: 0, Interp Count: 0
Thread Count: 0, Interp Count: 0
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 0, Interp Count: 0
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 0, Interp Count: 0
Thread Count: 0, Interp Count: 0
Thread Count: 1, Interp Count: 0
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 0, Interp Count: 0
Thread Count: 0, Interp Count: 0
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 0
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 0, Interp Count: 0
Thread Count: 1, Interp Count: 1
Thread Count: 0, Interp Count: 0
Thread Count: 0, Interp Count: 0
error: pthread_create() failed, exiting.

Fixed and merged in trunk 2014-04-23: see http://core.tcl.tk/tcl/tktview?name=3493120 Please verify again with current 8.6

Output of test-leak (compiled as: gcc -std=gnu11  -o test-leak test-leak.c -Wall -pthread -ltcl -I/usr/include  -L/usr/lib64):

$ ./test-leak 
Thread Count: 0, Interp Count: 0
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 2, Interp Count: 2
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 0, Interp Count: 0
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Thread Count: 1, Interp Count: 1
Tcl_InitNotifier: unable to start notifier thread
Aborted
$