diff --git a/include/maxscale/query_classifier.h b/include/maxscale/query_classifier.h
index 101a6ce6d..589687b3c 100644
--- a/include/maxscale/query_classifier.h
+++ b/include/maxscale/query_classifier.h
@@ -128,10 +128,11 @@ typedef struct qc_field_info
 typedef struct query_classifier
 {
     bool (*qc_setup)(const char* args);
-    bool (*qc_init)(void);
-    void (*qc_end)(void);
 
-    bool (*qc_thread_init)(void);
+    int (*qc_process_init)(void);
+    void (*qc_process_end)(void);
+
+    int (*qc_thread_init)(void);
     void (*qc_thread_end)(void);
 
     qc_parse_result_t (*qc_parse)(GWBUF* stmt);
@@ -152,10 +153,12 @@ typedef struct query_classifier
 } QUERY_CLASSIFIER;
 
 /**
- * Loads and initializes the default query classifier.
+ * Loads and sets up the default query classifier.
  *
  * This must be called once during the execution of a process. The query
- * classifier functions can only be used if this function returns true.
+ * classifier functions can only be used if this function first and thereafter
+ * the @c qc_process_init return true.
+ *
  * MaxScale calls this function, so plugins should not do that.
  *
  * @param plugin_name  The name of the plugin from which the query classifier
@@ -167,18 +170,32 @@ typedef struct query_classifier
  *
  * @see qc_end qc_thread_init
  */
-bool qc_init(const char* plugin_name, const char* plugin_args);
+bool qc_setup(const char* plugin_name, const char* plugin_args);
 
 /**
- * Finalizes and unloads the query classifier.
+ * Intializes the query classifier.
+ *
+ * This function should be called once, provided @c qc_setup returned true,
+ * before the query classifier functionality is used.
+ *
+ * MaxScale calls this functions, so plugins should not do that.
+ *
+ * @return True, if the process wide initialization could be performed.
+ *
+ * @see qc_process_end qc_thread_init
+ */
+bool qc_process_init(void);
+
+/**
+ * Finalizes the query classifier.
  *
  * A successful call of qc_init() should before program exit be followed
  * by a call to this function. MaxScale calls this function, so plugins
  * should not do that.
  *
- * @see qc_init qc_thread_end
+ * @see qc_process_init qc_thread_end
  */
-void qc_end(void);
+void qc_process_end(void);
 
 /**
  * Loads a particular query classifier.
@@ -206,10 +223,11 @@ QUERY_CLASSIFIER* qc_load(const char* plugin_name);
 void qc_unload(QUERY_CLASSIFIER* classifier);
 
 /**
- * Performs thread initialization needed by the query classifier.
- * Should be called in every thread, except the one where qc_init()
- * was called. MaxScale calls this function, so plugins should not
- * do that.
+ * Performs thread initialization needed by the query classifier. Should
+ * be called in every thread, except the one where qc_process_init()
+ * was called.
+ *
+ * MaxScale calls this function, so plugins should not do that.
  *
  * @return True if the initialization succeeded, false otherwise.
  *
@@ -220,8 +238,9 @@ bool qc_thread_init(void);
 /**
  * Performs thread finalization needed by the query classifier.
  * A successful call to qc_thread_init() should at some point be followed
- * by a call to this function. MaxScale calls this function, so plugins
- * should not do that.
+ * by a call to this function.
+ *
+ * MaxScale calls this function, so plugins should not do that.
  *
  * @see qc_thread_init
  */
diff --git a/query_classifier/qc_dummy/qc_dummy.cc b/query_classifier/qc_dummy/qc_dummy.cc
index 719edce2e..eed448169 100644
--- a/query_classifier/qc_dummy/qc_dummy.cc
+++ b/query_classifier/qc_dummy/qc_dummy.cc
@@ -83,21 +83,21 @@ bool qc_setup(const char* args)
     return true;
 }
 
-bool qc_init(void)
+int qc_dummy_process_init(void)
 {
-    return true;
+    return 0;
 }
 
-void qc_end(void)
+void qc_dummy_process_end(void)
 {
 }
 
-bool qc_thread_init(void)
+int qc_dummy_thread_init(void)
 {
-    return true;
+    return 0;
 }
 
-void qc_thread_end(void)
+void qc_dummy_thread_end(void)
 {
 }
 
@@ -108,10 +108,10 @@ extern "C"
         static QUERY_CLASSIFIER qc =
         {
             qc_setup,
-            qc_init,
-            qc_end,
-            qc_thread_init,
-            qc_thread_end,
+            qc_dummy_process_init,
+            qc_dummy_process_end,
+            qc_dummy_thread_init,
+            qc_dummy_thread_end,
             qc_parse,
             qc_get_type,
             qc_get_operation,
@@ -135,10 +135,10 @@ extern "C"
             "Dummy Query Classifier",
             "V1.0.0",
             &qc,
-            NULL, /* Process init. */
-            NULL, /* Process finish. */
-            NULL, /* Thread init. */
-            NULL, /* Thread finish. */
+            qc_dummy_process_init,
+            qc_dummy_process_end,
+            qc_dummy_thread_init,
+            qc_dummy_thread_end,
             {
                 {MXS_END_MODULE_PARAMS}
             }
diff --git a/query_classifier/qc_mysqlembedded/qc_mysqlembedded.cc b/query_classifier/qc_mysqlembedded/qc_mysqlembedded.cc
index 2363c8691..cc90cb5cb 100644
--- a/query_classifier/qc_mysqlembedded/qc_mysqlembedded.cc
+++ b/query_classifier/qc_mysqlembedded/qc_mysqlembedded.cc
@@ -2477,7 +2477,7 @@ void configure_options(const char* datadir, const char* langdir)
     server_options[IDX_DATADIR] = datadir_arg;
 
     rv = sprintf(language_arg, "--language=%s", langdir);
-    ss_dassert(rv < OPTIONS_LANGUAGE_SIZE); // Ensured by qc_init().
+    ss_dassert(rv < OPTIONS_LANGUAGE_SIZE); // Ensured by qc_process_init().
     server_options[IDX_LANGUAGE] = language_arg;
 
     // To prevent warning of unused variable when built in release mode,
@@ -2498,7 +2498,7 @@ bool qc_setup(const char* args)
     return true;
 }
 
-bool qc_init(void)
+int qc_mysql_process_init(void)
 {
     bool inited = false;
 
@@ -2530,15 +2530,15 @@ bool qc_init(void)
         }
     }
 
-    return inited;
+    return inited ? 0 : -1;
 }
 
-void qc_end(void)
+void qc_mysql_process_end(void)
 {
     mysql_library_end();
 }
 
-bool qc_thread_init(void)
+int qc_mysql_thread_init(void)
 {
     bool inited = (mysql_thread_init() == 0);
 
@@ -2547,10 +2547,10 @@ bool qc_thread_init(void)
         MXS_ERROR("mysql_thread_init() failed.");
     }
 
-    return inited;
+    return inited ? 0 : -1;
 }
 
-void qc_thread_end(void)
+void qc_mysql_thread_end(void)
 {
     mysql_thread_end();
 }
@@ -2567,10 +2567,10 @@ MXS_MODULE* MXS_CREATE_MODULE()
     static QUERY_CLASSIFIER qc =
     {
         qc_setup,
-        qc_init,
-        qc_end,
-        qc_thread_init,
-        qc_thread_end,
+        qc_mysql_process_init,
+        qc_mysql_process_end,
+        qc_mysql_thread_init,
+        qc_mysql_thread_end,
         qc_parse,
         qc_get_type,
         qc_get_operation,
@@ -2594,10 +2594,10 @@ MXS_MODULE* MXS_CREATE_MODULE()
         "Query classifier based upon MySQL Embedded",
         "V1.0.0",
         &qc,
-        NULL, /* Process init. */
-        NULL, /* Process finish. */
-        NULL, /* Thread init. */
-        NULL, /* Thread finish. */
+        qc_mysql_process_init,
+        qc_mysql_process_end,
+        qc_mysql_thread_init,
+        qc_mysql_thread_end,
         {
             {MXS_END_MODULE_PARAMS}
         }
diff --git a/query_classifier/qc_sqlite/qc_sqlite.c b/query_classifier/qc_sqlite/qc_sqlite.c
index f90bc34ea..e63d8078f 100644
--- a/query_classifier/qc_sqlite/qc_sqlite.c
+++ b/query_classifier/qc_sqlite/qc_sqlite.c
@@ -2598,9 +2598,9 @@ void maxscaleUse(Parse* pParse, Token* pToken)
  * API
  */
 static bool qc_sqlite_setup(const char* args);
-static bool qc_sqlite_init(void);
-static void qc_sqlite_end(void);
-static bool qc_sqlite_thread_init(void);
+static int qc_sqlite_process_init(void);
+static void qc_sqlite_process_end(void);
+static int qc_sqlite_thread_init(void);
 static void qc_sqlite_thread_end(void);
 static qc_parse_result_t qc_sqlite_parse(GWBUF* query);
 static uint32_t qc_sqlite_get_type(GWBUF* query);
@@ -2680,7 +2680,7 @@ static bool qc_sqlite_setup(const char* args)
     return this_unit.setup;
 }
 
-static bool qc_sqlite_init(void)
+static int qc_sqlite_process_init(void)
 {
     QC_TRACE();
     assert(this_unit.setup);
@@ -2692,7 +2692,7 @@ static bool qc_sqlite_init(void)
 
         this_unit.initialized = true;
 
-        if (qc_sqlite_thread_init())
+        if (qc_sqlite_thread_init() == 0)
         {
             if (this_unit.log_level != QC_LOG_NOTHING)
             {
@@ -2731,10 +2731,10 @@ static bool qc_sqlite_init(void)
         MXS_ERROR("Failed to initialize sqlite3.");
     }
 
-    return this_unit.initialized;
+    return this_unit.initialized ? 0 : -1;
 }
 
-static void qc_sqlite_end(void)
+static void qc_sqlite_process_end(void)
 {
     QC_TRACE();
     ss_dassert(this_unit.initialized);
@@ -2747,7 +2747,7 @@ static void qc_sqlite_end(void)
     this_unit.initialized = false;
 }
 
-static bool qc_sqlite_thread_init(void)
+static int qc_sqlite_thread_init(void)
 {
     QC_TRACE();
     ss_dassert(this_unit.initialized);
@@ -2798,7 +2798,7 @@ static bool qc_sqlite_thread_init(void)
                   (unsigned long) pthread_self(), rc, sqlite3_errstr(rc));
     }
 
-    return this_thread.initialized;
+    return this_thread.initialized ? 0 : -1;
 }
 
 static void qc_sqlite_thread_end(void)
@@ -3190,8 +3190,8 @@ MXS_MODULE* MXS_CREATE_MODULE()
     static QUERY_CLASSIFIER qc =
     {
         qc_sqlite_setup,
-        qc_sqlite_init,
-        qc_sqlite_end,
+        qc_sqlite_process_init,
+        qc_sqlite_process_end,
         qc_sqlite_thread_init,
         qc_sqlite_thread_end,
         qc_sqlite_parse,
@@ -3217,10 +3217,10 @@ MXS_MODULE* MXS_CREATE_MODULE()
         "Query classifier using sqlite.",
         "V1.0.0",
         &qc,
-        NULL, /* Process init. */
-        NULL, /* Process finish. */
-        NULL, /* Thread init. */
-        NULL, /* Thread finish. */
+        qc_sqlite_process_init,
+        qc_sqlite_process_end,
+        qc_sqlite_thread_init,
+        qc_sqlite_thread_end,
         {
             {MXS_END_MODULE_PARAMS}
         }
diff --git a/query_classifier/test/canonical_tests/canonizer.c b/query_classifier/test/canonical_tests/canonizer.c
index 56c59f1ea..a6d4d4db9 100644
--- a/query_classifier/test/canonical_tests/canonizer.c
+++ b/query_classifier/test/canonical_tests/canonizer.c
@@ -46,8 +46,8 @@ int main(int argc, char** argv)
     set_langdir(strdup("."));
     set_process_datadir(strdup("/tmp"));
 
-    qc_init("qc_sqlite", NULL);
-    qc_thread_init();
+    qc_setup("qc_sqlite", NULL);
+    qc_process_init();
 
     infile = fopen(argv[1],"rb");
     outfile = fopen(argv[2],"wb");
@@ -83,7 +83,6 @@ int main(int argc, char** argv)
     }
     fclose(infile);
     fclose(outfile);
-    qc_thread_end();
-    qc_end();
+    qc_process_end();
     return 0;
 }
diff --git a/query_classifier/test/classify.c b/query_classifier/test/classify.c
index c656abae3..7fe74d39d 100644
--- a/query_classifier/test/classify.c
+++ b/query_classifier/test/classify.c
@@ -314,10 +314,10 @@ int main(int argc, char** argv)
 
         if (mxs_log_init(NULL, ".", MXS_LOG_TARGET_DEFAULT))
         {
-            if (qc_init(lib, NULL))
+            if (qc_setup(lib, NULL) && qc_process_init())
             {
                 rc = run(input_name, expected_name);
-                qc_end();
+                qc_process_end();
             }
             else
             {
diff --git a/query_classifier/test/compare.cc b/query_classifier/test/compare.cc
index ba7847b2c..40e558700 100644
--- a/query_classifier/test/compare.cc
+++ b/query_classifier/test/compare.cc
@@ -163,7 +163,7 @@ QUERY_CLASSIFIER* get_classifier(const char* zName, const char* zArgs)
 
     if (pClassifier)
     {
-        if (!pClassifier->qc_setup(zArgs) || !pClassifier->qc_init())
+        if (!pClassifier->qc_setup(zArgs) || (pClassifier->qc_process_init() != 0))
         {
             cerr << "error: Could not setup or init classifier " << zName << "." << endl;
             qc_unload(pClassifier);
@@ -178,7 +178,7 @@ void put_classifier(QUERY_CLASSIFIER* pClassifier)
 {
     if (pClassifier)
     {
-        pClassifier->qc_end();
+        pClassifier->qc_process_end();
         qc_unload(pClassifier);
     }
 }
diff --git a/query_classifier/test/crash_qc_sqlite.c b/query_classifier/test/crash_qc_sqlite.c
index db4b67dd5..dff7cbd3d 100644
--- a/query_classifier/test/crash_qc_sqlite.c
+++ b/query_classifier/test/crash_qc_sqlite.c
@@ -41,7 +41,7 @@ int main()
 
     set_libdir(strdup("../qc_sqlite"));
 
-    if (qc_init("qc_sqlite", NULL))
+    if (qc_setup("qc_sqlite", NULL) && qc_process_init())
     {
         const char s[] = "SELECT @@global.max_allowed_packet";
 
@@ -53,7 +53,7 @@ int main()
         // code generator.
         qc_parse(stmt);
 
-        qc_end();
+        qc_process_end();
 
         rv = EXIT_SUCCESS;
     }
diff --git a/server/core/gateway.cc b/server/core/gateway.cc
index c42c9fdb3..0419545a7 100644
--- a/server/core/gateway.cc
+++ b/server/core/gateway.cc
@@ -976,26 +976,17 @@ void worker_thread_main(void* arg)
 {
     if (modules_thread_init())
     {
-        if (qc_thread_init())
+        /** Init mysql thread context for use with a mysql handle and a parser */
+        if (mysql_thread_init() == 0)
         {
-            /** Init mysql thread context for use with a mysql handle and a parser */
-            if (mysql_thread_init() == 0)
-            {
-                poll_waitevents(arg);
+            poll_waitevents(arg);
 
-                /** Release mysql thread context */
-                mysql_thread_end();
-            }
-            else
-            {
-                MXS_ERROR("Could not perform thread initialization for MySQL. Exiting thread.");
-            }
-
-            qc_thread_end();
+            /** Release mysql thread context */
+            mysql_thread_end();
         }
         else
         {
-            MXS_ERROR("Could not perform thread initialization for query classifier. Exiting thread.");
+            MXS_ERROR("Could not perform thread initialization for MySQL. Exiting thread.");
         }
 
         modules_thread_finish();
@@ -1875,7 +1866,7 @@ int main(int argc, char **argv)
     cnf = config_get_global_options();
     ss_dassert(cnf);
 
-    if (!qc_init(cnf->qc_name, cnf->qc_args))
+    if (!qc_setup(cnf->qc_name, cnf->qc_args))
     {
         const char* logerr = "Failed to initialise query classifier library.";
         print_log_n_stderr(true, true, logerr, logerr, eno);
@@ -2088,8 +2079,6 @@ int main(int argc, char **argv)
     /** Release mysql thread context*/
     mysql_thread_end();
 
-    qc_end();
-
     utils_end();
     cleanup_process_datadir();
     MXS_NOTICE("MaxScale shutdown completed.");
diff --git a/server/core/query_classifier.c b/server/core/query_classifier.c
index e7358f33f..4a0e2ecb8 100644
--- a/server/core/query_classifier.c
+++ b/server/core/query_classifier.c
@@ -38,7 +38,7 @@ static const char default_qc_name[] = "qc_sqlite";
 static QUERY_CLASSIFIER* classifier;
 
 
-bool qc_init(const char* plugin_name, const char* plugin_args)
+bool qc_setup(const char* plugin_name, const char* plugin_args)
 {
     QC_TRACE();
     ss_dassert(!classifier);
@@ -56,21 +56,30 @@ bool qc_init(const char* plugin_name, const char* plugin_args)
     {
         success = classifier->qc_setup(plugin_args);
 
-        if (success)
+        if (!success)
         {
-            success = classifier->qc_init();
+            qc_unload(classifier);
+            classifier = NULL;
         }
     }
 
     return success;
 }
 
-void qc_end(void)
+bool qc_process_init(void)
 {
     QC_TRACE();
     ss_dassert(classifier);
 
-    classifier->qc_end();
+    return classifier->qc_process_init() == 0;
+}
+
+void qc_process_end(void)
+{
+    QC_TRACE();
+    ss_dassert(classifier);
+
+    classifier->qc_process_end();
     classifier = NULL;
 }
 
@@ -101,7 +110,7 @@ bool qc_thread_init(void)
     QC_TRACE();
     ss_dassert(classifier);
 
-    return classifier->qc_thread_init();
+    return classifier->qc_thread_init() == 0;
 }
 
 void qc_thread_end(void)
diff --git a/server/modules/filter/cache/test/testkeygeneration.cc b/server/modules/filter/cache/test/testkeygeneration.cc
index d2bba2f85..aedc3501b 100644
--- a/server/modules/filter/cache/test/testkeygeneration.cc
+++ b/server/modules/filter/cache/test/testkeygeneration.cc
@@ -127,7 +127,7 @@ int main(int argc, char* argv[])
     {
         if (mxs_log_init(NULL, ".", MXS_LOG_TARGET_DEFAULT))
         {
-            if (qc_init(NULL, NULL))
+            if (qc_setup(NULL, NULL) && qc_process_init())
             {
                 const char* zModule = argv[1];
 
@@ -157,6 +157,8 @@ int main(int argc, char* argv[])
                 {
                     cerr << "error: Could not initialize factory." << endl;
                 }
+
+                qc_process_end();
             }
             else
             {
diff --git a/server/modules/filter/cache/test/testrules.cc b/server/modules/filter/cache/test/testrules.cc
index c613305a8..c73157a79 100644
--- a/server/modules/filter/cache/test/testrules.cc
+++ b/server/modules/filter/cache/test/testrules.cc
@@ -237,10 +237,12 @@ int main()
     if (mxs_log_init(NULL, ".", MXS_LOG_TARGET_DEFAULT))
     {
         set_libdir(MXS_STRDUP_A("../../../../../query_classifier/qc_sqlite/"));
-        if (qc_init("qc_sqlite", ""))
+        if (qc_setup("qc_sqlite", "") && qc_process_init())
         {
             set_libdir(MXS_STRDUP_A("../"));
             rc = test();
+
+            qc_process_end();
         }
         else
         {
diff --git a/server/modules/filter/cache/test/teststorage.cc b/server/modules/filter/cache/test/teststorage.cc
index c7dc68d1c..d6cffc687 100644
--- a/server/modules/filter/cache/test/teststorage.cc
+++ b/server/modules/filter/cache/test/teststorage.cc
@@ -50,7 +50,7 @@ int TestStorage::run(int argc, char** argv)
     {
         if (mxs_log_init(NULL, ".", MXS_LOG_TARGET_DEFAULT))
         {
-            if (qc_init(NULL, NULL))
+            if (qc_setup(NULL, NULL) && qc_process_init())
             {
                 const char* zModule = NULL;
                 size_t threads = m_threads;