Overview
--------

Stress script is designed to perform testsing of mysql server in 
multi-thread environment. 

Stress script allows:
 
 - to use for stress testing mysqltest binary as test engine
 - to use for stress testing both regular test suite and any
   additional test suites (e.g. mysql-test-extra-5.0)
 - to specify files with lists of tests both for initialization of
   stress db and for further testing itself
 - to define number of threads that will be concurrently used in testing
 - to define limitations for test run. e.g. number of tests or loops
   for execution or duration of testing, delay between test executions, etc.
 - to get readable log file which can be used for identification of
   errors arose during testing

All functionality regarding stress testing was implemeted in 
mysql-stress-test.pl script and there are two ways to run stress test:

 - for most cases it is enough to use options below for starting of
   stress test from mysql-test-run wrapper. In this case server will 
   be run automatically, all preparation steps will be performed
   and after that stress test will be started.

 - in advanced case one can run mysql-stress-test.pl script directly. 
   But it requires to perform some preparation steps and to specify a 
   bunch of options as well so this way may look a bit complicate.

Usage
-----

Below is list of stress test specific options for mysql-test-run:

--stress 
  Enable stress mode

--stress-suite=<suite name>
  Test suite name that will be used in stress testing.
  We assume that all suites are located in mysql-test/suite directory
  There is one special suite name - <main|default> that corresponds
  to regular test suite located in mysql-test directory. 
  
--stress-threads=<number of threads>
  Number of threads that will be used in stress testing
  
--stress-tests-file=<filename with list of tests>
  Filename with list of tests(without .test suffix) that will be used in 
  stress testing. Default filename is stress_tests.txt and default 
  location of this file is suite/<suite name>/stress_tests.txt

--stress-init-file=<filename with list of tests>
  Filename with list of tests(without .test suffix) that will be used in 
  stress testing for initialization of stress db. These tests will be 
  executed only once before starting of test itself. Default filename 
  is stress_init.txt and default location of this file is 
  suite/<suite name>/stress_init.txt

--stress-mode=<method which will be used for choosing tests from the list>
  Possible values are: random(default), seq 

  There are two possible modes which affect order of selecting of tests
  from the list:
    - in random mode tests will be selected in random order
    - in seq mode each thread will execute tests in the loop one by one as
      they specified in the list file.

--stress-test-count= <number>
  Total number of tests that will be executed concurrently by all threads

--stress-loop-count= <number>
  Total number of loops in seq mode that will be executed concurrently 
  by all threads

--stress-test-duration= <number>
  Duration of stress testing in seconds

Examples
-------- 

1. Example of simple command line to start stress test:

 mysql-test-run --stress alias

Runs stress test with default values for number of threads and number of tests,
with test 'alias' from suite 'main'.

2. Using in stress testing tests from other suites:

 - mysql-test-run --stress --stress-threads=10 --stress-test-count=1000 \
                 --stress-suite=example  --stress-tests-file=testslist.txt

   Will run stress test with 10 threads, will execute 1000 tests by all 
   threads, test will be used from suite 'example', list of test will be 
   taken from file 'testslist.txt'

 - mysql-test-run --stress --stress-threads=10 --stress-test-count=1000 \
                  --stress-suite=example sum_distinct

   Will run stress test with 10 threads, will execute 1000 tests by all 
   threads, test will be used from suite 'example', list of test contains 
   only one test 'sum_distinct'

3. Debugging of issues found with stress test

 Right now stress test is not fully integrated in mysql-test-run
 and does not support --gdb option so to debug issue found with stress 
 test you have to start separately mysql server under debuger and then 
 run stress test as:
 
 - mysql-test-run --extern --stress --stress-threads=10 \
                  --stress-test-count=1000 --stress-suite=example \
                  sum_distinct