# percona-server-5.6-5.6.27-76.0/storage/innobase/btr/btr0sea.cc line 705

**URL:** <https://forums.percona.com/t/percona-server-5-6-5-6-27-76-0-storage-innobase-btr-btr0sea-cc-line-705/4782>\
**Category:** Other MySQL® Questions\
**Created:** [March 15, 2016, 10:09am UTC](https://forums.percona.com/t/percona-server-5-6-5-6-27-76-0-storage-innobase-btr-btr0sea-cc-line-705/4782 "2016-03-15T10:09:49Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![susantomahato88](https://sea1.discourse-cdn.com/flex019/user_avatar/forums.percona.com/susantomahato88/32/1050_2.png) [@susantomahato88](https://forums.percona.com/u/susantomahato88)\
**Post date:** [March 15, 2016, 10:09am UTC](https://forums.percona.com/t/percona-server-5-6-5-6-27-76-0-storage-innobase-btr-btr0sea-cc-line-705/4782/1 "2016-03-15T10:09:49Z")

</div>

Last time write locked in file /mnt/workspace/percona-server-5.6-debian-binary/label\_exp/ubuntu-trusty-64bit/percona-server-5.6-5.6.27-76.0/storage/innobase/btr/btr0sea.cc line 705  
–Thread 140629718189824 has waited at row0ins.cc line 2718 for 1.0000 seconds the semaphore:  
X-lock on RW-latch at 0x7feae0f2c640 ‘&block-\>lock’  
a writer (thread id 140629766379264) has reserved it in mode exclusive  
number of readers 0, waiters flag 1, lock\_word: 0  
Last time read locked in file buf0flu.cc line 1078

Last time write locked in file /mnt/workspace/percona-server-5.6-debian-binary/label\_exp/ubuntu-trusty-64bit/percona-server-5.6-5.6.27-76.0/storage/innobase/row/row0ins.cc line 2718  
–Thread 140633553512192 has waited at row0ins.cc line 2718 for 1.0000 seconds the semaphore:  
X-lock on RW-latch at 0x7feae0f2c640 ‘&block-\>lock’  
a writer (thread id 140629766379264) has reserved it in mode exclusive  
number of readers 0, waiters flag 1, lock\_word: 0  
Last time read locked in file buf0flu.cc line 1078

Can you please mention what is the issue here?

---

<div class="post-metadata">

**Author:** ![rodrigo](https://avatars.discourse-cdn.com/v4/letter/r/4af34b/32.png) [@rodrigo](https://forums.percona.com/u/rodrigo)\
**Post date:** [September 11, 2017, 8:53am UTC](https://forums.percona.com/t/percona-server-5-6-5-6-27-76-0-storage-innobase-btr-btr0sea-cc-line-705/4782/2 "2017-09-11T08:53:45Z")

</div>

I seem to have the same issue here… Is there a filed bug for this?  
Thanks

---

<div class="post-metadata">

**Author:** ![miguelangelnieto](https://avatars.discourse-cdn.com/v4/letter/m/b9e5f3/32.png) [@miguelangelnieto](https://forums.percona.com/u/miguelangelnieto)\
**Post date:** [September 20, 2017, 7:40am UTC](https://forums.percona.com/t/percona-server-5-6-5-6-27-76-0-storage-innobase-btr-btr0sea-cc-line-705/4782/3 "2017-09-20T07:40:58Z")

</div>

Looks like you are having too much concurrency and therefore some threads have to wait on mutexes. This one:

rw\_lock\_x\_lock(btr\_search\_get\_latch(cursor-\>index));

Semaphores and low waits are normal if many threads try to access the same data. With the info shared it is not possible to give an detailed reply, but I would recommend you to test limiting innodb\_thread\_concurrency to the number of cores. Also, I would recommend you to upgrade to latest version. The one you are running is two years old. Tons of bug has been fixed and performance improvements applied since then.