Re: [naviserver-devel] Quest for malloc

[Vlad Seryakov]

I tried to run this program, it crahses with all allocators on free when 
it was allocated in other thread. zippy does it as well, i amnot sure 
how Naviserver works then.

#include <tcl.h>

#define MemAlloc ckalloc
#define MemFree ckfree

int nbuffer = 16384;
int nloops = 50000;
int nthreads = 4;

int gAllocs = 0;
void *gPtr = NULL;
Tcl_Mutex gLock;

void MemThread(void *arg)
{
    int   i,n;
    void *ptr = NULL;

    for (i = 0; i < nloops; ++i) {
        n = 1 + (int) (nbuffer * (rand() / (RAND_MAX + 1.0)));
        if (ptr != NULL) {
            MemFree(ptr);
        }
        ptr = MemAlloc(n);
        // Testing inter-thread alloc/free
        if (n % 5 == 0) {
            Tcl_MutexLock(&gLock);
            if (gPtr != NULL) {
                MemFree(gPtr);
            }
            gPtr = MemAlloc(n);
            gAllocs++;
            Tcl_MutexUnlock(&gLock);
        }
    }
    if (ptr != NULL) {
        MemFree(ptr);
    }
    if (gPtr != NULL) {
        MemFree(gPtr);
    }
}

void MemTime()
{
    int           i;
    Tcl_ThreadId *tids;
    tids = (Tcl_ThreadId *)malloc(sizeof(Tcl_ThreadId) * nthreads);

    for (i = 0; i < nthreads; ++i) {
        Tcl_CreateThread( &tids[i], MemThread, NULL, 
TCL_THREAD_STACK_DEFAULT, TCL_THREAD_JOINABLE);
    }
    for (i = 0; i < nthreads; ++i) {
        Tcl_JoinThread(tids[i], NULL);
    }
}

int main (int argc, char **argv)
{
   MemTime();
}


Doesn't zippy also clear it's per-thread cache on exit?


It puts blocks into shared queue which other threads can re-use.
But shared cache never gets returned so conn threads exit will not help 
with memory bloat.


--
Vlad Seryakov
571 262-8608 office
[EMAIL PROTECTED]
http://www.crystalballinc.com/vlad/