线上一台mysql 5.7.17版本实例，系统centos 6.4 ，96G内存，SSD磁盘，buffer pool 60G，buffer pool instance 8，24 CPU。实例访问情况如下：

不定期的夯住重启，每次状态都是一致，error log如下输出：

nnoDB: ###### Diagnostic info printed to the standard error stream

2017-05-01T19:21:24.095658+08:00 0 [Warning] InnoDB: A long semaphore wait:

--Thread 139927055582976 has waited at buf0flu.cc line 1209 for 303.00 seconds the semaphore:

SX-lock on RW-latch at 0x7f448b83aa70 created in file buf0buf.cc line 1459

a writer (thread id 139928763602688) has reserved it in mode exclusive

number of readers 0, waiters flag 1, lock_word: 0

Last time read locked in file row0sel.cc line 3652

Last time write locked in file /export/home/pb2/build/sb_0-21378219-1480347226.17/mysql-5.7.17/storage/innobase/btr/btr0cur.cc line 299

2017-05-01T19:21:24.095746+08:00 0 [Warning] InnoDB: A long semaphore wait:

--Thread 139927087052544 has waited at buf0flu.cc line 1209 for 303.00 seconds the semaphore:

SX-lock on RW-latch at 0x7f463e8eeb08 created in file buf0buf.cc line 1459

a writer (thread id 139928763602688) has reserved it in mode exclusive

number of readers 0, waiters flag 1, lock_word: 0

Last time read locked in file row0sel.cc line 3652

Last time write locked in file /export/home/pb2/build/sb_0-21378219-1480347226.17/mysql-5.7.17/storage/innobase/btr/btr0cur.cc line 315

2017-05-01T19:21:24.095798+08:00 0 [Warning] InnoDB: A long semaphore wait:

--Thread 139921740433152 has waited at row0ins.cc line 2481 for 303.00 seconds the semaphore:

S-lock on RW-latch at 0x7f49d5fc2be8 created in file buf0buf.cc line 1459

a writer (thread id 139928763602688) has reserved it in mode exclusive

number of readers 0, waiters flag 1, lock_word: 0

Last time read locked in file row0ins.cc line 2481

Last time write locked in file /export/home/pb2/build/sb_0-21378219-1480347226.17/mysql-5.7.17/storage/innobase/include/mtr0mtr.ic line 153

2017-05-01T19:21:24.095871+08:00 0 [Warning] InnoDB: A long semaphore wait:

--Thread 139921726056192 has waited at row0ins.cc line 2481 for 303.00 seconds the semaphore:

S-lock on RW-latch at 0x7f49d5fc2be8 created in file buf0buf.cc line 1459

a writer (thread id 139928763602688) has reserved it in mode exclusive

number of readers 0, waiters flag 1, lock_word: 0

Last time read locked in file row0ins.cc line 2481

Last time write locked in file /export/home/pb2/build/sb_0-21378219-1480347226.17/mysql-5.7.17/storage/innobase/include/mtr0mtr.ic line 153

2017-05-01T19:21:24.095917+08:00 0 [Warning] InnoDB: A long semaphore wait:

--Thread 139921718867712 has waited at row0ins.cc line 2481 for 303.00 seconds the semaphore:

S-lock on RW-latch at 0x7f49d5fc2be8 created in file buf0buf.cc line 1459

a writer (thread id 139928763602688) has reserved it in mode exclusive

number of readers 0, waiters flag 1, lock_word: 0

Last time read locked in file row0ins.cc line 2481

Last time write locked in file /export/home/pb2/build/sb_0-21378219-1480347226.17/mysql-5.7.17/storage/innobase/include/mtr0mtr.ic line 153

2017-05-01T19:21:24.095959+08:00 0 [Warning] InnoDB: A long semaphore wait:

--Thread 139927097542400 has waited at buf0flu.cc line 1209 for 303.00 seconds the semaphore:

SX-lock on RW-latch at 0x7f49d5fc2be8 created in file buf0buf.cc line 1459

a writer (thread id 139928763602688) has reserved it in mode exclusive

number of readers 0, waiters flag 1, lock_word: 0

Last time read locked in file row0ins.cc line 2481

Last time write locked in file /export/home/pb2/build/sb_0-21378219-1480347226.17/mysql-5.7.17/storage/innobase/include/mtr0mtr.ic line 153

从日志看，是长时间的信号等待触发了重启，之前5.7.13版本也出现，升级到5.7.17还是一样。

最开始怀疑是系统信号集设置不够，从250 32000 32 128 调整到2500 3200000 3200 1280，

还是出现了重启。从日志中看都在等待139928763602688 线程，从日志的下文可以得到该线程只是一条简单的insert语句，并没有其他异常查询，而且每次夯住时的语句并不相同。此外该实例之前运行在5.5版本下，没出现过该问题。请问该问题应该如何处理？