diff --git a/pjlib/src/pjlib-test/ioq_perf.c b/pjlib/src/pjlib-test/ioq_perf.c
index bf0e627..fea9c18 100644
--- a/pjlib/src/pjlib-test/ioq_perf.c
+++ b/pjlib/src/pjlib-test/ioq_perf.c
@@ -398,8 +398,6 @@
     for (i=0; i<sockpair_cnt; ++i) {
         pj_ioqueue_unregister(items[i].server_key);
         pj_ioqueue_unregister(items[i].client_key);
-        pj_sock_close(items[i].server_fd);
-        pj_sock_close(items[i].client_fd);
     }
 
     /* Destroy threads */
diff --git a/pjlib/src/pjlib-test/ioq_udp.c b/pjlib/src/pjlib-test/ioq_udp.c
index b81764f..89e2a1e 100644
--- a/pjlib/src/pjlib-test/ioq_udp.c
+++ b/pjlib/src/pjlib-test/ioq_udp.c
@@ -457,7 +457,6 @@
 
     /* Now unregister and close socket. */
     pj_ioqueue_unregister(key);
-    pj_sock_close(rsock);
 
     /* Poll ioqueue. */
     timeout.sec = 1; timeout.msec = 0;
@@ -539,10 +538,6 @@
 	if (rc != PJ_SUCCESS) {
 	    app_perror("...error in pj_ioqueue_unregister", rc);
 	}
-	rc = pj_sock_close(sock[i]);
-	if (rc != PJ_SUCCESS) {
-	    app_perror("...error in pj_sock_close", rc);
-	}
     }
 
     rc = pj_ioqueue_destroy(ioqueue);
diff --git a/pjlib/src/pjlib-test/ioq_unreg.c b/pjlib/src/pjlib-test/ioq_unreg.c
new file mode 100644
index 0000000..475d62f
--- /dev/null
+++ b/pjlib/src/pjlib-test/ioq_unreg.c
@@ -0,0 +1,361 @@
+/* $Id$ */
+/* 
+ * Copyright (C)2003-2006 Benny Prijono <benny@prijono.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 
+ */
+#include "test.h"
+
+#if INCLUDE_IOQUEUE_UNREG_TEST
+/*
+ * This tests the thread safety of ioqueue unregistration operation.
+ */
+
+#include <pj/errno.h>
+#include <pj/ioqueue.h>
+#include <pj/log.h>
+#include <pj/os.h>
+#include <pj/pool.h>
+#include <pj/sock.h>
+#include <pj/compat/socket.h>
+#include <pj/string.h>
+
+
+#define THIS_FILE   "ioq_unreg.c"
+
+
+enum test_method
+{
+    UNREGISTER_IN_APP,
+    UNREGISTER_IN_CALLBACK,
+};
+
+static int thread_quitting;
+static enum test_method test_method;
+static pj_time_val time_to_unregister;
+
+struct sock_data
+{
+    pj_sock_t		 sock;
+    pj_sock_t		 csock;
+    pj_pool_t		*pool;
+    pj_ioqueue_key_t	*key;
+    pj_mutex_t		*mutex;
+    pj_ioqueue_op_key_t	*op_key;
+    char		*buffer;
+    pj_size_t		 bufsize;
+    pj_bool_t		 unregistered;
+    unsigned		 received;
+} sock_data;
+
+static void on_read_complete(pj_ioqueue_key_t *key, 
+                             pj_ioqueue_op_key_t *op_key, 
+                             pj_ssize_t bytes_read)
+{
+    pj_ssize_t size;
+    char *sendbuf = "Hello world";
+    pj_status_t status;
+
+    if (sock_data.unregistered)
+	return;
+
+    pj_mutex_lock(sock_data.mutex);
+
+    if (sock_data.unregistered) {
+	/* No need to unlock. Mutex may have been destroyed */
+	return;
+    }
+
+    if (bytes_read < 0) {
+	if (-bytes_read != PJ_STATUS_FROM_OS(OSERR_EWOULDBLOCK))
+	    app_perror("ioqueue reported recv error", -bytes_read);
+    } else {
+	sock_data.received += bytes_read;
+    }
+
+    if (test_method == UNREGISTER_IN_CALLBACK) {
+	pj_time_val now;
+
+	pj_gettimeofday(&now);
+	if (PJ_TIME_VAL_GTE(now, time_to_unregister)) { 
+	    sock_data.unregistered = 1;
+	    pj_ioqueue_unregister(key);
+	    pj_mutex_destroy(sock_data.mutex);
+	    pj_pool_release(sock_data.pool);
+	    sock_data.pool = NULL;
+	    return;
+	}
+    }
+ 
+    do { 
+	size = sock_data.bufsize;
+	status = pj_ioqueue_recv(key, op_key, sock_data.buffer, &size, 0);
+	if (status != PJ_EPENDING && status != PJ_SUCCESS)
+	    app_perror("recv() error", status);
+
+    } while (status == PJ_SUCCESS);
+
+    pj_mutex_unlock(sock_data.mutex);
+
+    size = pj_ansi_strlen(sendbuf);
+    status = pj_sock_send(sock_data.csock, sendbuf, &size, 0);
+    if (status != PJ_SUCCESS)
+	app_perror("send() error", status);
+
+    size = pj_ansi_strlen(sendbuf);
+    status = pj_sock_send(sock_data.csock, sendbuf, &size, 0);
+    if (status != PJ_SUCCESS)
+	app_perror("send() error", status);
+
+} 
+
+static int worker_thread(void *arg)
+{
+    pj_ioqueue_t *ioqueue = arg;
+
+    while (!thread_quitting) {
+	pj_time_val timeout = { 0, 20 };
+	pj_ioqueue_poll(ioqueue, &timeout);
+    }
+
+    return 0;
+}
+
+/*
+ * Perform unregistration test.
+ *
+ * This will create ioqueue and register a server socket. Depending
+ * on the test method, either the callback or the main thread will
+ * unregister and destroy the server socket after some period of time.
+ */
+static int perform_unreg_test(pj_ioqueue_t *ioqueue,
+			      pj_pool_t *test_pool,
+			      const char *title, 
+			      pj_bool_t other_socket)
+{
+    enum { WORKER_CNT = 1, MSEC = 500, QUIT_MSEC = 500 };
+    int i;
+    pj_thread_t *thread[WORKER_CNT];
+    struct sock_data osd;
+    pj_ioqueue_callback callback;
+    pj_time_val end_time;
+    pj_status_t status;
+
+
+    /* Sometimes its important to have other sockets registered to
+     * the ioqueue, because when no sockets are registered, the ioqueue
+     * will return from the poll early.
+     */
+    if (other_socket) {
+	status = app_socket(PJ_AF_INET, PJ_SOCK_DGRAM, 0, 56127, &osd.sock);
+	if (status != PJ_SUCCESS) {
+	    app_perror("Error creating other socket", status);
+	    return -12;
+	}
+
+	pj_memset(&callback, 0, sizeof(callback));
+	status = pj_ioqueue_register_sock(test_pool, ioqueue, osd.sock,
+					  NULL, &callback, &osd.key);
+	if (status != PJ_SUCCESS) {
+	    app_perror("Error registering other socket", status);
+	    return -13;
+	}
+
+    } else {
+	osd.key = NULL;
+	osd.sock = PJ_INVALID_SOCKET;
+    }
+
+    /* Init both time duration of testing */
+    thread_quitting = 0;
+    pj_gettimeofday(&time_to_unregister);
+    time_to_unregister.msec += MSEC;
+    pj_time_val_normalize(&time_to_unregister);
+
+    end_time = time_to_unregister;
+    end_time.msec += QUIT_MSEC;
+    pj_time_val_normalize(&end_time);
+
+    
+    /* Create polling thread */
+    for (i=0; i<WORKER_CNT; ++i) {
+	status = pj_thread_create(test_pool, "unregtest", &worker_thread,
+				   ioqueue, 0, 0, &thread[i]);
+	if (status != PJ_SUCCESS) {
+	    app_perror("Error creating thread", status);
+	    return -20;
+	}
+    }
+
+    /* Create pair of client/server sockets */
+    status = app_socketpair(PJ_AF_INET, PJ_SOCK_DGRAM, 0, 
+			    &sock_data.sock, &sock_data.csock);
+    if (status != PJ_SUCCESS) {
+	app_perror("app_socketpair error", status);
+	return -30;
+    }
+
+
+    /* Initialize test data */
+    sock_data.pool = pj_pool_create(mem, "sd", 1000, 1000, NULL);
+    sock_data.buffer = pj_pool_alloc(sock_data.pool, 128);
+    sock_data.bufsize = 128;
+    sock_data.op_key = pj_pool_alloc(sock_data.pool, 
+				     sizeof(*sock_data.op_key));
+    sock_data.received = 0;
+    sock_data.unregistered = 0;
+
+    pj_ioqueue_op_key_init(sock_data.op_key, sizeof(*sock_data.op_key));
+
+    status = pj_mutex_create_simple(sock_data.pool, "sd", &sock_data.mutex);
+    if (status != PJ_SUCCESS) {
+	app_perror("create_mutex() error", status);
+	return -35;
+    }
+
+    /* Register socket to ioqueue */
+    pj_memset(&callback, 0, sizeof(callback));
+    callback.on_read_complete = &on_read_complete;
+    status = pj_ioqueue_register_sock(sock_data.pool, ioqueue, sock_data.sock,
+				      NULL, &callback, &sock_data.key);
+    if (status != PJ_SUCCESS) {
+	app_perror("pj_ioqueue_register error", status);
+	return -40;
+    }
+
+    /* Bootstrap the first send/receive */
+    on_read_complete(sock_data.key, sock_data.op_key, 0);
+
+    /* Loop until test time ends */
+    for (;;) {
+	pj_time_val now, timeout;
+
+	pj_gettimeofday(&now);
+
+	if (test_method == UNREGISTER_IN_APP && 
+	    PJ_TIME_VAL_GTE(now, time_to_unregister) &&
+	    sock_data.pool) 
+	{
+	    pj_mutex_lock(sock_data.mutex);
+
+	    sock_data.unregistered = 1;
+	    pj_ioqueue_unregister(sock_data.key);
+	    pj_mutex_destroy(sock_data.mutex);
+	    pj_pool_release(sock_data.pool);
+	    sock_data.pool = NULL;
+	}
+
+	if (PJ_TIME_VAL_GT(now, end_time) && sock_data.unregistered)
+	    break;
+
+	timeout.sec = 0; timeout.msec = 10;
+	pj_ioqueue_poll(ioqueue, &timeout);
+	//pj_thread_sleep(1);
+
+    }
+
+    thread_quitting = 1;
+
+    for (i=0; i<WORKER_CNT; ++i) {
+	pj_thread_join(thread[i]);
+	pj_thread_destroy(thread[i]);
+    }
+
+    if (other_socket) {
+	pj_ioqueue_unregister(osd.key);
+    }
+
+    pj_sock_close(sock_data.csock);
+
+    PJ_LOG(3,(THIS_FILE, "....%s: done (%d KB/s)",
+	      title, sock_data.received * 1000 / MSEC / 1000));
+    return 0;
+}
+
+int udp_ioqueue_unreg_test(void)
+{
+    enum { LOOP = 10 };
+    int i, rc;
+    char title[30];
+    pj_ioqueue_t *ioqueue;
+    pj_pool_t *test_pool;
+			      
+    test_method = UNREGISTER_IN_APP;
+
+    test_pool = pj_pool_create(mem, "unregtest", 4000, 4000, NULL);
+
+    rc = pj_ioqueue_create(test_pool, 16, &ioqueue);
+    if (rc != PJ_SUCCESS) {
+	app_perror("Error creating ioqueue", rc);
+	return -10;
+    }
+
+
+    PJ_LOG(3, (THIS_FILE, "...ioqueue unregister stress test 0/3 (%s)", 
+	       pj_ioqueue_name()));
+    for (i=0; i<LOOP; ++i) {
+	pj_ansi_sprintf(title, "repeat %d/%d", i, LOOP);
+	rc = perform_unreg_test(ioqueue, test_pool, title, 0);
+	if (rc != 0)
+	    return rc;
+    }
+
+
+    PJ_LOG(3, (THIS_FILE, "...ioqueue unregister stress test 1/3 (%s)",
+	       pj_ioqueue_name()));
+    for (i=0; i<LOOP; ++i) {
+	pj_ansi_sprintf(title, "repeat %d/%d", i, LOOP);
+	rc = perform_unreg_test(ioqueue, test_pool, title, 1);
+	if (rc != 0)
+	    return rc;
+    }
+
+    test_method = UNREGISTER_IN_CALLBACK;
+
+    PJ_LOG(3, (THIS_FILE, "...ioqueue unregister stress test 2/3 (%s)", 
+	       pj_ioqueue_name()));
+    for (i=0; i<LOOP; ++i) {
+	pj_ansi_sprintf(title, "repeat %d/%d", i, LOOP);
+	rc = perform_unreg_test(ioqueue, test_pool, title, 0);
+	if (rc != 0)
+	    return rc;
+    }
+
+
+    PJ_LOG(3, (THIS_FILE, "...ioqueue unregister stress test 3/3 (%s)", 
+	       pj_ioqueue_name()));
+    for (i=0; i<LOOP; ++i) {
+	pj_ansi_sprintf(title, "repeat %d/%d", i, LOOP);
+	rc = perform_unreg_test(ioqueue, test_pool, title, 1);
+	if (rc != 0)
+	    return rc;
+    }
+
+    pj_ioqueue_destroy(ioqueue);
+    pj_pool_release(test_pool);
+
+    return 0;
+}
+
+
+
+#else
+/* To prevent warning about "translation unit is empty"
+ * when this test is disabled. 
+ */
+int dummy_uiq_unreg;
+#endif	/* INCLUDE_IOQUEUE_UNREG_TEST */
+
+
diff --git a/pjlib/src/pjlib-test/test.c b/pjlib/src/pjlib-test/test.c
index 1d504ae..97ba299 100644
--- a/pjlib/src/pjlib-test/test.c
+++ b/pjlib/src/pjlib-test/test.c
@@ -145,6 +145,10 @@
     DO_TEST( ioqueue_perf_test() );
 #endif
 
+#if INCLUDE_IOQUEUE_UNREG_TEST
+    DO_TEST( udp_ioqueue_unreg_test() );
+#endif
+
 #if INCLUDE_FILE_TEST
     DO_TEST( file_test() );
 #endif
diff --git a/pjlib/src/pjlib-test/test.h b/pjlib/src/pjlib-test/test.h
index 8571d9d..7a0aeed 100644
--- a/pjlib/src/pjlib-test/test.h
+++ b/pjlib/src/pjlib-test/test.h
@@ -48,6 +48,7 @@
 #define INCLUDE_UDP_IOQUEUE_TEST    GROUP_NETWORK
 #define INCLUDE_TCP_IOQUEUE_TEST    GROUP_NETWORK
 #define INCLUDE_IOQUEUE_PERF_TEST   GROUP_NETWORK
+#define INCLUDE_IOQUEUE_UNREG_TEST  GROUP_NETWORK
 #define INCLUDE_FILE_TEST           GROUP_FILE
 
 #define INCLUDE_ECHO_SERVER         0
@@ -82,6 +83,7 @@
 extern int sock_perf_test(void);
 extern int select_test(void);
 extern int udp_ioqueue_test(void);
+extern int udp_ioqueue_unreg_test(void);
 extern int tcp_ioqueue_test(void);
 extern int ioqueue_perf_test(void);
 extern int file_test(void);