Don't crash on destroy() when process was forked (#1674)

src/rdkafka.c

@@ -734,7 +734,10 @@ static void rd_kafka_destroy_app (rd_kafka_t *rk, int blocking) {
                      "Joining main background thread");
 
         if (thrd_join(thrd, NULL) != thrd_success)
-                rd_kafka_assert(NULL, !*"failed to join main thread");
+                rd_kafka_log(rk, LOG_ERR, "DESTROY",
+                             "Failed to join main thread: %s "
+                             "(was process forked?)",
+                             rd_strerror(errno));
 
         rd_kafka_destroy_final(rk);
 }

tests/0079-fork.c

@@ -0,0 +1,91 @@
+/*
+ * librdkafka - Apache Kafka C library
+ *
+ * Copyright (c) 2012-2015, Magnus Edenhill
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "test.h"
+#include "rdkafka.h"
+
+#ifndef _MSC_VER
+#include <unistd.h>
+#include <sys/wait.h>
+#endif
+
+/**
+ * @brief Forking a threaded process will not transfer threads (such as
+ *        librdkafka's background threads) to the child process.
+ *        There is no way such a forked client instance will work
+ *        in the child process, but it should not crash on destruction: #1674
+ */
+
+int main_0079_fork (int argc, char **argv) {
+#ifdef _MSC_VER
+        TEST_SKIP("No fork() support on Windows");
+        return 0;
+#else
+        pid_t pid;
+        rd_kafka_t *rk;
+        int status;
+
+        rk = test_create_producer();
+
+        rd_kafka_producev(rk,
+                          RD_KAFKA_V_TOPIC("atopic"),
+                          RD_KAFKA_V_VALUE("hi", 2),
+                          RD_KAFKA_V_END);
+
+        pid = fork();
+        TEST_ASSERT(pid != 1, "fork() failed: %s", strerror(errno));
+
+        if (pid == 0) {
+                /* Child process */
+
+                /* This call will enqueue the message on a queue
+                 * which is not served by any thread, but it should not crash */
+                rd_kafka_producev(rk,
+                                  RD_KAFKA_V_TOPIC("atopic"),
+                                  RD_KAFKA_V_VALUE("hello", 5),
+                                  RD_KAFKA_V_END);
+
+                /* Don't crash on us */
+                rd_kafka_destroy(rk);
+
+                exit(0);
+        }
+
+        /* Parent process, wait for child to exit cleanly. */
+        if (waitpid(pid, &status, 0) == -1)
+                TEST_FAIL("waitpid(%d) failed: %s", (int)pid, strerror(errno));
+
+        if (!WIFEXITED(status) ||
+            WEXITSTATUS(status) != 0)
+                TEST_FAIL("child exited with status %d", WEXITSTATUS(status));
+
+        rd_kafka_destroy(rk);
+
+        return 0;
+#endif
+}

tests/CMakeLists.txt

@@ -71,6 +71,7 @@ set(
     0076-produce_retry.c
     0077-compaction.c
     0078-c_from_cpp.cpp
+    0079-fork.c
     8000-idle.cpp
     test.c
     testcpp.cpp    

tests/test.c

@@ -163,6 +163,7 @@ _TEST_DECL(0075_retry);
 _TEST_DECL(0076_produce_retry);
 _TEST_DECL(0077_compaction);
 _TEST_DECL(0078_c_from_cpp);
+_TEST_DECL(0079_fork);
 
 
 /* Manual tests */
@@ -261,6 +262,7 @@ struct test tests[] = {
         _TEST(0076_produce_retry, 0),
         _TEST(0077_compaction, 0, TEST_BRKVER(0,9,0,0)),
         _TEST(0078_c_from_cpp, TEST_F_LOCAL),
+        _TEST(0079_fork, TEST_F_LOCAL|TEST_F_KNOWN_ISSUE_WIN32),
 
         /* Manual tests */
         _TEST(8000_idle, TEST_F_MANUAL),

win32/tests/tests.vcxproj

@@ -162,6 +162,7 @@
     <ClCompile Include="..\..\tests\0076-produce_retry.c" />
     <ClCompile Include="..\..\tests\0077-compaction.c" />
     <ClCompile Include="..\..\tests\0078-c_from_cpp.cpp" />
+    <ClCompile Include="..\..\tests\0079-fork.c" />
     <ClCompile Include="..\..\tests\8000-idle.cpp" />
     <ClCompile Include="..\..\tests\test.c" />
     <ClCompile Include="..\..\tests\testcpp.cpp" />