From: Ole John Aske
Date: August 14 2012 11:25am
Subject: bzr push into mysql-5.5-cluster-7.2 branch (ole.john.aske:3974 to 3975)
 Bug#14489398
List-Archive: http://lists.mysql.com/commits/144561
X-Bug: 14489398
Message-Id: <20120814112548.15961.56448.3975@fimafeng09.no.oracle.com>
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 3975 Ole John Aske	2012-08-14
      Fix for Bug#14489398 CLUSTER BACKUP FAILS WHEN USING NDBMTD AND CONFIGURED MULTIPLE LQHS
      
      Fix regression introduced by push:
      
      3923 Ole John Aske	2012-05-23
            This is the improved 'save_mem.patch' from Mikael R. patch set
      
      That push tried to save memory used for interthread communication buffers
      by not allocated buffers between those threads which was assumed to not communicate.
      LDM <-> LDM communication was one of the places where such buffers where removed.
      
      However, the BACKUP-block is part of the LDM thread, and during backup the 
      first BACKUP instance in LDM thread#1 will act as client/coordinator. Thus
      it *will* communicate with other LDM threads!
      
      This fix introduce special handling of LDM thread#1, and 'opens up' communication
      between that thread and other LDM threads. Instead of writing a completely new
      testcase to cover this fix, I have introduced 'ndb_restore_misc.cnf' which overrides
      'MaxNoOfExecutionThreads=4' - Such that at least one of the existing backup-restore
      tests are run with multiple LDM threads.
      
      If the BACKUP is later made full multithreaded, the changes to mt.cpp in
      this patch should be reverted.

    added:
      mysql-test/suite/ndb/t/ndb_restore_misc.cnf
    modified:
      storage/ndb/src/kernel/vm/mt.cpp
 3974 Frazer Clement	2012-08-13 [merge]
      Merge 7.1->7.2

    modified:
      storage/ndb/src/kernel/blocks/dblqh/DblqhMain.cpp
=== added file 'mysql-test/suite/ndb/t/ndb_restore_misc.cnf'
--- a/mysql-test/suite/ndb/t/ndb_restore_misc.cnf	1970-01-01 00:00:00 +0000
+++ b/mysql-test/suite/ndb/t/ndb_restore_misc.cnf	2012-08-14 11:23:36 +0000
@@ -0,0 +1,7 @@
+!include suite/ndb/my.cnf
+
+[cluster_config]
+# If MT-ndb, there should be multiple BACKUP blocks
+# (There is one pr LDM)
+MaxNoOfExecutionThreads=4
+

=== modified file 'storage/ndb/src/kernel/vm/mt.cpp'
--- a/storage/ndb/src/kernel/vm/mt.cpp	2012-06-18 13:54:07 +0000
+++ b/storage/ndb/src/kernel/vm/mt.cpp	2012-08-14 11:23:36 +0000
@@ -4068,6 +4068,17 @@ is_ldm_thread(unsigned thr_no)
          thr_no <  NUM_MAIN_THREADS+globalData.ndbMtLqhThreads;
 }
 
+/**
+ * All LDM threads are not created equal: 
+ * First LDMs BACKUP-thread act as client during BACKUP
+ * (See usage of Backup::UserBackupInstanceKey)
+ */
+static bool
+is_first_ldm_thread(unsigned thr_no)
+{
+  return thr_no == NUM_MAIN_THREADS;
+}
+
 static bool
 is_tc_thread(unsigned thr_no)
 {
@@ -4099,9 +4110,16 @@ may_communicate(unsigned from, unsigned 
   }
   else if (is_ldm_thread(from))
   {
-    // LQH threads can communicates with TC-, main- and itself
+    // First LDM is special as it may act as internal client
+    // during backup, and thus communicate with other LDMs:
+    if (is_first_ldm_thread(from) && is_ldm_thread(to))
+      return true;
+
+    // All LDM threads can communicates with TC-, main-
+    // itself, and the BACKUP client (above) 
     return is_main_thread(to) ||
            is_tc_thread(to)   ||
+           is_first_ldm_thread(to) ||
            (to == from);
   }
   else if (is_tc_thread(from))
@@ -4426,6 +4444,14 @@ compute_jb_pages(struct EmulatorData * e
          job_queue_pages_per_thread;
 
   /**
+   * First LDM thread is special as it will act as client
+   * during backup. It will send to, and receive from (2x) 
+   * the 'num_lqh_threads - 1' other LQH threads.
+   */
+  tot += 2 * (num_lqh_threads-1) *
+         job_queue_pages_per_thread;
+
+  /**
    * TC threads can communicate with SPJ-, LQH- and main threads.
    * Cannot communicate with receive threads and other TC threads,
    * but as SPJ is located together with TC, it is counted as it

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