SEMAPHORESエラーが出力されDBクエリの処理ができなくなる。

内容：最近になってDBのクエリ処理が正常に行えない状態なり
　　：WEBサイトが見れなくなる事象が発生しています。
　　：DBサーバのMySQLを再起動すると事象は解消しますが、
　　：不規則的なタイミングで事象が頻繁に再発しております。
　　：
　　：mysqlのログにはINNODB MONITOR OUTPUTが出力され
　　：SEMAPHORESに関するエラーが出力されております。
　　：何か改善案などあれば教えていただきたいです。
　　：
—————————————————————————
=====================================
211220 14:25:39 INNODB MONITOR OUTPUT
=====================================
Per second averages calculated from the last 62 seconds
—————–
BACKGROUND THREAD
—————–
srv_master_thread loops: 140956 1_second, 140956 sleeps, 12900 10_second, 12235 background, 12235 flush
srv_master_thread log flush and writes: 140981
———-
SEMAPHORES
———-
OS WAIT ARRAY INFO: reservation count 133669, signal count 26092
–Thread 140063310575360 has waited at trx0undo.ic line 156 for 249.00 seconds the semaphore:
X-lock (wait_ex) on RW-latch at 0x7f63872b37c0 created in file buf0buf.c line 938
a writer (thread id 140063310575360) has reserved it in mode wait exclusive
number of readers 1, waiters flag 0, lock_word: ffffffffffffffff
Last time read locked in file buf0flu.c line 1319
Last time write locked in file /builddir/build/BUILD/mysql-5.5.47/storage/innobase/include/trx0undo.ic line 156
–Thread 140063875819264 has waited at btr0pcur.c line 425 for 243.00 seconds the semaphore:
S-lock on RW-latch at 0x7f63661765c0 created in file buf0buf.c line 938
a writer (thread id 140063310575360) has reserved it in mode exclusive
number of readers 0, waiters flag 1, lock_word: 0
Last time read locked in file row0sel.c line 2930
Last time write locked in file /builddir/build/BUILD/mysql-5.5.47/storage/innobase/row/row0upd.c line 2144
–Thread 140063874221824 has waited at btr0pcur.c line 425 for 238.00 seconds the semaphore:
S-lock on RW-latch at 0x7f63661765c0 created in file buf0buf.c line 938
a writer (thread id 140063310575360) has reserved it in mode exclusive
number of readers 0, waiters flag 1, lock_word: 0
Last time read locked in file row0sel.c line 2930
Last time write locked in file /builddir/build/BUILD/mysql-5.5.47/storage/innobase/row/row0upd.c line 2144
–Thread 140063877949184 has waited at btr0pcur.c line 425 for 235.00 seconds the semaphore:
S-lock on RW-latch at 0x7f63661765c0 created in file buf0buf.c line 938
a writer (thread id 140063310575360) has reserved it in mode exclusive
number of readers 0, waiters flag 1, lock_word: 0
Last time read locked in file row0sel.c line 2930
—————————————————————————

▼サーバ情報　WEBサーバとDBサーバで分離しています。
■WEBサーバ
Apache 　　　　　　　：Apache/2.2.15 (Unix)
PHP　　　　　　　　　：5.5.31
wordpressのバージョン：5.8.1

■DBサーバ
MySQL 　　　　　　　：5.5.47