Merge branch '2.3' into 2.4

system-test/mxs1985_kill_hang.cpp

@@ -0,0 +1,55 @@
+/**
+ * MXS-1985: MaxScale hangs on concurrent KILL processing
+ */
+
+#include <maxtest/testconnections.hh>
+
+#include <atomic>
+#include <thread>
+#include <iostream>
+
+using namespace std;
+
+static atomic<bool> running {true};
+
+int main(int argc, char* argv[])
+{
+    TestConnections test(argc, argv);
+    vector<thread> threads;
+
+    for (int i = 0; i < 20 && test.global_result == 0; i++)
+    {
+        threads.emplace_back([&, i]() {
+                                 while (running && test.global_result == 0)
+                                 {
+                                     MYSQL* c = test.maxscales->open_rwsplit_connection();
+
+                                    // It doesn't really matter if the connection ID exists, this is just a
+                                    // handy way of generating cross-thread communication.
+                                     for (auto&& a : get_result(c,
+                                                                "SELECT id FROM information_schema.processlist"
+                                                                " WHERE user like '%skysql%'"))
+                                     {
+                                         if (execute_query_silent(c, std::string("KILL " + a[0]).c_str()))
+                                         {
+                                             break;
+                                         }
+                                     }
+
+                                     mysql_close(c);
+                                 }
+                             });
+    }
+
+    sleep(10);
+    running = false;
+
+    // If MaxScale hangs, at least one thread will not return in time
+    test.set_timeout(30);
+    for (auto&& a : threads)
+    {
+        a.join();
+    }
+
+    return test.global_result;
+}