MySQL Bugs: #34517: SHOW GLOBAL STATUS does not work properly in embedded server.

Bug #34517	SHOW GLOBAL STATUS does not work properly in embedded server.
Submitted:	13 Feb 2008 9:50	Modified:	1 Feb 2009 0:07
Reporter:	Alexander Nozdrin	Email Updates:
Status:	Closed	Impact on me:	None
Category:	MySQL Server: Embedded Library ( libmysqld )	Severity:	S3 (Non-critical)
Version:	5.1	OS:	Any
Assigned to:	Alexey Botchkov	CPU Architecture:	Any

Description:
SHOW GLOBAL STATUS does not take into account session-scope values
when run in embedded server.

How to repeat:
1. Create the following test file:

mysql-test/t/qqq.test
------------------
SHOW GLOBAL STATUS LIKE 'com_select';
SHOW STATUS LIKE 'com_select';

SELECT 1;

SHOW GLOBAL STATUS LIKE 'com_select';
SHOW STATUS LIKE 'com_select';
------------------

2. Run under the test suite, create result file:
> ./mtr --record qqq

3. mysql-test/r/qqq.result should be like:
-------------------
SHOW GLOBAL STATUS LIKE 'com_select';
Variable_name   Value
Com_select      0

SHOW STATUS LIKE 'com_select';
Variable_name   Value
Com_select      0

SELECT 1;
1
1

SHOW GLOBAL STATUS LIKE 'com_select';
Variable_name   Value
Com_select      1

SHOW STATUS LIKE 'com_select';
Variable_name   Value
Com_select      1
-------------------

Note, that SHOW GLOBAL STATUS and SHOW STATUS return the same results.

4. Execute qqq.test under the test suite in embedded mode:
> ./mtr --embedded qqq

There will be the following diff:
-------------------
 SHOW GLOBAL STATUS LIKE 'com_select';
 Variable_name  Value
-Com_select     1
+Com_select     0
 SHOW STATUS LIKE 'com_select';
 Variable_name  Value
 Com_select     1
-------------------

The problem is that SHOW GLOBAL STATUS returns 0 (that's a bug),
while SHOW STATUS returns 1 (that's correct).

Suggested fix:
SHOW GLOBAL STATUS "is implemented" in sql_show.cc:calc_sum_of_all_status()
function.

The idea of that function is that it takes global values and then iterates
through all thread/sessions and add their values. Threads/sessions are
registered in the global variable 'threads', defined in mysqld.cc
(I_List<THD> threads;). The problem seems that threads is empty in embedded
mode, i.e. 'dummy embedded thread' is not registered in this list.

Verified as described.

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/44361

ChangeSet@1.2601, 2008-03-24 17:41:59+04:00, holyfoot@mysql.com +1 -0
  Bug#34517 SHOW GLOBAL STATUS does not work properly in embedded server.
  
  GLOBAL STATUS is calculated by studying the list of threads. In the
  embedded server threads were not linked to the internal list, so the
  calculation always returns 0. Fixed by 'linking' the embedded-server
  threads to the same list.

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/44362

ChangeSet@1.2570, 2008-03-24 17:43:20+04:00, holyfoot@mysql.com +2 -0
  Bug #34517 SHOW GLOBAL STATUS does not work properly in embedded server.
  
  test case added

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/53301

2728 Alexey Botchkov	2008-09-05
      Bug#34517 SHOW GLOBAL STATUS does not work properly in embedded server.
        
        GLOBAL STATUS is calculated by studying the list of threads. In the
        embedded server threads were not linked to the internal list, so the
        calculation always returns 0. Fixed by 'linking' the embedded-server
        threads to the same list
      
      per-file comments
      
      libmysqld/lib_sql.cc
          Bug#34517 SHOW GLOBAL STATUS does not work properly in embedded server.
          
          Add newly created 'threads' to the internal thread list.
          Remove them from the list as they're freed.
      
      mysql-test/r/information_schema.result
              test result
      
      mysql-test/t/information_schema.test
              test case

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/58976

2711 Alexey Botchkov	2008-11-17
      Bug#34517 SHOW GLOBAL STATUS does not work properly in embedded server.
      
            GLOBAL STATUS is calculated by studying the list of threads. In the
              embedded server threads were not linked to the internal list, so the
              calculation always returns 0. Fixed by 'linking' the embedded-server
              threads to the same list
      
      per-file comments:
        libmysqld/lib_sql.cc
      Bug#34517 SHOW GLOBAL STATUS does not work properly in embedded server.
          Add newly created 'threads' to the internal thread list.
          Remove them from the list as they're freed.
      
        mysql-test/r/information_schema.result
      Bug#34517 SHOW GLOBAL STATUS does not work properly in embedded server.
          test result
      
        mysql-test/t/information_schema.test
      Bug#34517 SHOW GLOBAL STATUS does not work properly in embedded server.
          test case added

Pushed into 5.1.31  (revid:holyfoot@mysql.com-20081117160603-637w82fvmw0sulox) (version source revid:patrick.crews@sun.com-20081126180318-v685u61mpgoc176x) (pib:5)

Pushed into 6.0.9-alpha  (revid:holyfoot@mysql.com-20081117160603-637w82fvmw0sulox) (version source revid:ingo.struewing@sun.com-20081121151447-dtf2ofz2ys0zqed1) (pib:5)

Noted in 5.1.31, 6.0.9 changelog.

SHOW GLOBAL STATUS shows values that aggregate the session status
values for all threads. This did not work correctly for the embedded
server.

Pushed into 5.1.31-ndb-6.2.17 (revid:tomas.ulin@sun.com-20090119095303-uwwvxiibtr38djii) (version source revid:tomas.ulin@sun.com-20090108105244-8opp3i85jw0uj5ib) (merge vers: 5.1.31-ndb-6.2.17) (pib:6)

Pushed into 5.1.31-ndb-6.3.21 (revid:tomas.ulin@sun.com-20090119104956-guxz190n2kh31fxl) (version source revid:tomas.ulin@sun.com-20090119104956-guxz190n2kh31fxl) (merge vers: 5.1.31-ndb-6.3.21) (pib:6)

Pushed into 5.1.31-ndb-6.4.1 (revid:tomas.ulin@sun.com-20090119144033-4aylstx5czzz88i5) (version source revid:tomas.ulin@sun.com-20090119144033-4aylstx5czzz88i5) (merge vers: 5.1.31-ndb-6.4.1) (pib:6)

There are still comments in 5.1 main test cases about things that
should be fixed as this bug gets fixed.

Re-opening this bug, so that the test cases get fixed.

A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/64762

2769 Davi Arnaut	2009-01-31
      Remove duplicated test for Bug#34517

Closed as above patch hopefully fixes the issue.

Pushed into 5.1.32 (revid:joro@sun.com-20090203090549-gos3v4320vimrzg6) (version source revid:azundris@mysql.com-20090202131035-zuf2kdg8u8r177fi) (merge vers: 5.1.32) (pib:6)

Pushed into 6.0.10-alpha (revid:kostja@sun.com-20090204104420-mw1i2u9lum4bxjo6) (version source revid:joro@sun.com-20090201143058-0ddvdak8hydjz3od) (merge vers: 6.0.10-alpha) (pib:6)

Pushed into 5.1.32-ndb-6.3.23 (revid:tomas.ulin@sun.com-20090217131017-6u8qz1edkjfiobef) (version source revid:tomas.ulin@sun.com-20090203133556-9rclp06ol19bmzs4) (merge vers: 5.1.32-ndb-6.3.22) (pib:6)

Pushed into 5.1.32-ndb-6.4.3 (revid:tomas.ulin@sun.com-20090217134419-5ha6xg4dpedrbmau) (version source revid:tomas.ulin@sun.com-20090203133556-9rclp06ol19bmzs4) (merge vers: 5.1.32-ndb-6.3.22) (pib:6)

Pushed into 5.1.32-ndb-6.2.17 (revid:tomas.ulin@sun.com-20090217134216-5699eq74ws4oxa0j) (version source revid:tomas.ulin@sun.com-20090202111723-1zzwax187rtls913) (merge vers: 5.1.32-ndb-6.2.17) (pib:6)