Session causes allocation failure and GC in old space requested in a Node Program

<--- Last few GCs --->

114682552 ms: Mark-sweep 1315.8 (1392.1) -> 1226.1 (1392.1) MB, 2324.4 / 0.1 ms [allocation failure] [GC in old space requested]. 114685084 ms: Mark-sweep 1226.1 (1392.1) -> 1226.0 (1326.1) MB, 2532.7 / 0.0 ms [allocation failure] [GC in old space requested]. 114687590 ms: Mark-sweep 1226.0 (1326.1) -> 1225.1 (1280.1) MB, 2505.7 / 0.1 ms [last resort gc]. 114689995 ms: Mark-sweep 1225.1 (1280.1) -> 1224.3 (1280.1) MB, 2404.4 / 0.0 ms [last resort gc].

<--- JS stacktrace --->

==== JS stack trace =========================================

Security context: 0x1315b91cfb39 1: save [/home/iclassroom/nodejs/cnwkw/node_modules/express-session/session/session.js:~70] [pc=0x6fe4bba3671] (this=0x5dd90c06a41 ,fn=0x5dd90c08c31 )

2: save [/home/iclassroom/nodejs/cnwkw/node_modules/express-session/index.js:331] [pc=0x6fe3c6a7591] (this=0x5dd90c06a41 <a Session with map 0x12b2...

I don't understand why the bug happened.

via shuangjie zhu