tokudb hotbackup plugin

[Hu Zilin]

Can this plugin backup the InnoDB table under load?

I use sysbench prepare 7 tokudb table .
I alter one of these to InnoDB.

Then I pressure on MySQL with sysbench.

During the period i run `set tokudb_backup_dir='/home/hu/tokudb_hotbackup_test/bk';`.

After that I startup a MySQL instance with '/home/hu/tokudb_hotbackup_test/bk'.

Then the following error occurred:

```
2017-02-16T06:04:04.376762Z 0 [Note] InnoDB: Uncompressed page, stored checksum in field1 1217216326, calculated checksums for field1: crc32 1217216326/287156304, innodb 2359718055, none 3735928559, stored checksum in field2 1217216326, calculated checksums for field2: crc32 1217216326/287156304, innodb 79066636, none 3735928559, page LSN 0 1379770422, low 4 bytes of LSN at page end 1379770422, page number (if stored to page already) 15387, space id (if created with >= MySQL-4.1.1 and stored already) 0
InnoDB: Page may be a freshly allocated page
2017-02-16T06:04:04.376787Z 0 [ERROR] [FATAL] InnoDB: Apparent corruption of an index page [page id: space=0, page number=413] to be written to data file. We intentionally crash the server to prevent corrupt data from ending up in data files.
2017-02-16 14:04:04 0x7ff90ebf5700 InnoDB: Assertion failure in thread 140707671004928 in file ut0ut.cc line 917
InnoDB: We intentionally generate a memory trap.
InnoDB: Submit a detailed bug report to http://bugs.mysql.com.
InnoDB: If you get repeated assertion failures or crashes, even
InnoDB: immediately after the mysqld startup, there may be
InnoDB: corruption in the InnoDB tablespace. Please refer to
InnoDB: http://dev.mysql.com/doc/refman/5.7/en/forcing-innodb-recovery.html
InnoDB: about forcing recovery.
06:04:04 UTC - mysqld got signal 6 ;
This could be because you hit a bug. It is also possible that this binary
or one of the libraries it was linked against is corrupt, improperly built,
or misconfigured. This error can also be caused by malfunctioning hardware.
Attempting to collect some information that could help diagnose the problem.
As this is a crash and something is definitely wrong, the information
collection process might fail.
Please help us make Percona Server better by reporting any
bugs at http://bugs.percona.com/

key_buffer_size=8388608
read_buffer_size=131072
max_used_connections=0
max_threads=20481
thread_count=0
connection_count=0
It is possible that mysqld could use up to
key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 8160046 K bytes of memory
Hope that's ok; if not, decrease some variables in the equation.

Thread pointer: 0x0
Attempting backtrace. You can use the following information to find out
where mysqld died. If you see no messages after this, something went
terribly wrong...
stack_bottom = 0 thread_stack 0x40000
/home/hu/tokudb_hotbackup_test/Percona-Server-5.7.16-10-Linux.x86_64.ssl101/bin/mysqld(my_print_stacktrace+0x2c)[0xec814c]
/home/hu/tokudb_hotbackup_test/Percona-Server-5.7.16-10-Linux.x86_64.ssl101/bin/mysqld(handle_fatal_signal+0x461)[0x79e231]
/lib64/libpthread.so.0[0x3e8460f500]
/lib64/libc.so.6(gsignal+0x35)[0x3366c328a5]
/lib64/libc.so.6(abort+0x175)[0x3366c34085]
/home/hu/tokudb_hotbackup_test/Percona-Server-5.7.16-10-Linux.x86_64.ssl101/bin/mysqld[0x76cd28]
/home/hu/tokudb_hotbackup_test/Percona-Server-5.7.16-10-Linux.x86_64.ssl101/bin/mysqld(_ZN2ib5fatalD1Ev+0xee)[0x115d7ae]
/home/hu/tokudb_hotbackup_test/Percona-Server-5.7.16-10-Linux.x86_64.ssl101/bin/mysqld[0x11a6a2a]
/home/hu/tokudb_hotbackup_test/Percona-Server-5.7.16-10-Linux.x86_64.ssl101/bin/mysqld(_Z31buf_dblwr_flush_buffered_writesm+0x468)[0x11a8488]
Thu Feb 16 14:04:04 2017 PerconaFT recovery starting in env /home/hu/tokudb_hotbackup_test/data1/
/home/hu/tokudb_hotbackup_test/Percona-Server-5.7.16-10-Linux.x86_64.ssl101/bin/mysqld(_Z22buf_dblwr_add_to_batchP10buf_page_t11buf_flush_t+0x9a)[0x11a858a]
/home/hu/tokudb_hotbackup_test/Percona-Server-5.7.16-10-Linux.x86_64.ssl101/bin/mysqld(_Z14buf_flush_pageP10buf_pool_tP10buf_page_t11buf_flush_tb+0x84e)[0x11b8ace]
/home/hu/tokudb_hotbackup_test/Percona-Server-5.7.16-10-Linux.x86_64.ssl101/bin/mysqld[0x11b9383]
/home/hu/tokudb_hotbackup_test/Percona-Server-5.7.16-10-Linux.x86_64.ssl101/bin/mysqld(_Z18buf_flush_do_batchP10buf_pool_t11buf_flush_tmmPm+0x57f)[0x11ba97f]
/home/hu/tokudb_hotbackup_test/Percona-Server-5.7.16-10-Linux.x86_64.ssl101/bin/mysqld(buf_flush_page_cleaner_coordinator+0x15fc)[0x11bf00c]
```

[Shahriyar Rzayev (rzayev-sehriyar)]

Percona now uses JIRA for bug reports so this bug report is migrated to: https://jira.percona.com/browse/PS-3643