#endif

/*
 * The following variable is used to tell whether this module has been
 * initialized.
 */

static bool initialized = false;

/*
 * The pipeMutex locks around access to the initialized and procList
 * variables, and it is used to protect background threads from being
 * terminated while they are using APIs that hold locks.
 */

     * Check the initialized flag first, then check again in the mutex. This
     * is a speed enhancement.
     */

    if (!initialized) {
	Tcl_MutexLock(&pipeMutex);
	if (!initialized) {
	    initialized = true;
	    procList = NULL;
	}
	Tcl_MutexUnlock(&pipeMutex);
    }

    tsdPtr = (ThreadSpecificData *)TclThreadDataKeyGet(&dataKey);
    if (tsdPtr == NULL) {