lot of active connection cause mysql slow ?

hi, All
usually , our mysql server run status:
thread_connected about 1000, thread_running <10
recently , At 11:34 of every Saturday , when concurrent connection increased
thread_connected about 3000, thread_running = 1000
mysql server slow down, Almost stop read and write, continuous about 1 minutes.
After thread_running < 10, mysql read and write resume normal.

At problem time point, show engine innodb status show:
--Thread 139904453748480 has waited at btr0cur.cc line 586 for 0.0000 seconds the semaphore:
S-lock on RW-latch at 0x7f3ddae57a10 '&new_index->lock'
a writer (thread id 139906901120768) has reserved it in mode exclusive
number of readers 0, waiters flag 1, lock_word: 0
Last time read locked in file btr0cur.cc line 586
Last time write locked in file /home/buildbot/buildbot/build/mariadb-10.0.21/storage/xtradb/btr/btr0cur.cc line 577

pt-stalk capture files in Attachmens:mysql querstion.zip , please help analyze ,thanks.