Jemalloc memory profiling integration

[efirs]

This change provides low overhead way to get memory allocation statistics of the running instance.

One can get allocation summary using performance_schema.malloc_stats_summary table. Example:

mysql> select * from performance_schema.malloc_stats_summary;

+------------+------------+------------+------------+------------+-----------+
| ALLOCATED  | ACTIVE     | MAPPED     | RESIDENT   | RETAINED   | METADATA  |
+------------+------------+------------+------------+------------+-----------+
| 4444587952 | 5305044912 | 7284843752 | 5427371072 | 1237219680 | 196446784 |
+------------+------------+------------+------------+------------+-----------+
1 row in set (0.02 sec)

Or more detailed statistics by the allocation size and number of requests:

mysql> select * from performance_schema.malloc_stats;
+-------+------------+------------+---------+-------------+
| TYPE  | ALLOCATED  | NMALLOC    | NDALLOC | NREQUESTS   |
+-------+------------+------------+---------+-------------+
| small | 1981056488 | 1240672368 |       0 | 12119092401 |
| large |  344781832 |  101634376 |       0 |  2921581156 |
| huge  | 1904418320 |         53 |       0 |          53 |
+-------+------------+------------+---------+-------------+
3 rows in set (0.02 sec)

Most detailed view of the state of the memory can be produced by dumping memory profile:

mysql> show variables like '%jemalloc%';
+--------------------+-------+
| Variable_name      | Value |
+--------------------+-------+
| jemalloc_detected  | ON    |
| jemalloc_profiling | ON    |
+--------------------+-------+
2 rows in set (0.00 sec)

mysql> flush memory profile;
Query OK, 0 rows affected (0.01 sec)

[root@/ #]ls /tmp/jeprof_mysqld*
/tmp/jeprof_mysqld.1.0.170013202213
[root@/ #]jeprof --dot /usr/sbin/mysqld /tmp/jeprof_mysqld.1.0.170013202213 > /tmp/jeprof1.dot
[root@/ #]dot -Tpng /tmp/jeprof1.dot > /tmp/jeprof1.png

Here is an example of allocation graph: https://github.com/jemalloc/jemalloc/wiki/Use-Case%3A-Leak-Checking

Enabling profiling is a three fold process:

1. Jemalloc needs to be built with profiling enabled (./autogen.sh --enable-prof ...)
2. Jemalloc and profiling needs to be loaded on the instance start:
   LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libjemalloc.so.2 MALLOC_CONF="prof:true" mysqld &
3. Jemalloc_profiling option controls runtime state of the profiling(using SET GLOBAL), but so as enabled profiling has very little overhead it can be permanently enabled in my.cnf

Performance schema tables are available as soon as Jemalloc is loaded and mysql_upgrade --upgrade-system-tables has been executed for existing instances, no other configuration is needed.

[laurynas-biveinis]

@alexey2k, FYI

[dutow]

Hello!

I'm closing this pull request as it targets the 5.6 release. If it's still relevant to the 5.7/8.0 branch, please reopen it targeting either of them.

[LenzGr]

Looks like this was implemented in #4223