i started to play around with "thread_handling = pool-of-threads" with
10.2.7 and removed at that time the @mysqli_real_connect() error
supression of my database-layer which also has a usleep() and retry-loop
in case connection failed on so completly burried the issue
PHP Warning: mysqli_real_connect() [<a
href='http://at.php.net/manual/de/function.mysqli-real-connect.php'>function.mysqli-real-connect.php</a>]:
(HY000/2002): Resource temporarily unavailable
you should not see such messages when run a "ab -c 200 -n 500000 -k
http://corecms/show_content.php?sid=2"; with "max_connections = 300"
_____________________________________
thread_handling = one-thread-per-connection
[root@srv-rhsoft:~]$ cat php_error.log | wc -l
52596
thread_handling = pool-of-threads
thread_pool_idle_timeout = 900
[root@srv-rhsoft:~]$ cat php_error.log | wc -l
39282
thread_handling = pool-of-threads
thread_pool_oversubscribe = 10
thread_pool_idle_timeout = 900
thread_pool_priority = high
[root@srv-rhsoft:~]$ cat php_error.log | wc -l
24849
since my database-layer makes a usleep(100000) before each retry and the
retry-lop still has error-supression that means the cms waits 10% of all
requests at least 0.1 seconds for the mariadb server which means the
4300 Requests/Second could be much higher if every connection suceeds at
the first try (at least the thread pool seems to work slightly better
then without)
_____________________________________
what makes me really worry here is while the load is running (mysqld
each time restartet before start apache-benchmark)
+-------------------------+-------+
| Variable_name | Value |
+-------------------------+-------+
| Threadpool_idle_threads | 181 |
| Threadpool_threads | 189 |
+-------------------------+-------+
after the benchmark has finished and the machine is idle:
+-------------------------+-------+
| Variable_name | Value |
+-------------------------+-------+
| Threadpool_idle_threads | 207 |
| Threadpool_threads | 208 |
+-------------------------+-------+
frankly i would expect at least that this numbers are going up while the
load is running to at least 200 or not going up that high at all but
don't refuse conncetions which is IMHO the point of a pool
_____________________________________
the core-cms itself makes exactly two queries per request over 3 MyISAM
tables, one cache-table with a pirmary key and the second one is a
simple join on two tables with only 2 records, so not really something
one should call real load
select SQL_NO_CACHE * from cms1_cache where `hash`='fullmenu_1_2_0de0_0'
select SQL_NO_CACHE * from `cms1_sub` join `cms1_haupt` on sid=2 and
hid=shid
mysqld as well as httpd had "LimitNOFILE=infinity" in the systemd-unit,
the connection type is unix socket, so that all should not be a problem
on a i7-3770 CPU @ 3.40GHz with 32 GB RAM
it takes some time until the errors start to appear in the log, likely
after httpd (mod_prefork) had forked enough worker to introduce real
concurrency to the database
