# Retention policy deletion check let the memory explode **URL:** \ **Category:** Systems\ **Tags:** influxdb\ **Created:** [September 12, 2018, 8:52am UTC](https://community.influxdata.com/t/retention-policy-deletion-check-let-the-memory-explode/6558 "2018-09-12T08:52:24Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![zilongzhang](https://avatars.discourse-cdn.com/v4/letter/z/cc9497/32.png) [@zilongzhang](https://community.influxdata.com/u/zilongzhang)\ **Post date:** [September 12, 2018, 8:52am UTC](https://community.influxdata.com/t/retention-policy-deletion-check-let-the-memory-explode/6558/1 "2018-09-12T08:52:24Z")
I just start using influxdb(1.7) to collect cgroup measurement, and i find retention policy deletion check has a very expensive cost on memory and cpu, the influx log like below: ts=2018-09-12T00:08:01.600466Z lvl=info msg=“Retention policy deletion check (start)” log\_id=0AU6aqCG000 service=retention trace\_id=0AUmYLG0000 op\_name=retention\_delete\_check op\_event=start … s=2018-09-12T00:32:43.064925Z lvl=info msg=“Retention policy deletion check (end)” log\_id=0AU6aqCG000 service=retention trace\_id=0AUmYLG0000 op\_name=retention\_delete\_check op\_event=end op\_elapsed=1481464.468ms … ts=2018-09-12T01:08:01.600467Z lvl=info msg=“Retention policy deletion check (start)” log\_id=0AU6aqCG000 service=retention trace\_id=0AUpz3l0000 op\_name=retention\_delete\_check op\_event=start … ts=2018-09-12T01:50:50.442853Z lvl=info msg=“Retention policy deletion check (end)” log\_id=0AU6aqCG000 service=retention trace\_id=0AUpz3l0000 op\_name=retention\_delete\_check op\_event=end op\_elapsed=2568842.397ms ts=2018-09-12T01:50:50.442905Z lvl=info msg=“Retention policy deletion check (start)” log\_id=0AU6aqCG000 service=retention trace\_id=0AUsQrIW000 op\_name=retention\_delete\_check op\_event=start ts=2018-09-12T01:50:50.443269Z lvl=info msg=“Retention policy deletion check (end)” log\_id=0AU6aqCG000 service=retention trace\_id=0AUsQrIW000 op\_name=retention\_delete\_check op\_event=end op\_elapsed=0.370ms when i watch the heap size on the chrongraf,it looks like this: ![image](https://us1.discourse-cdn.com/flex023/uploads/influxdata/original/2X/1/134bb3ef711a5824eca708603d48b4b5c05c96fb.png) cpu also has the same performance: here is some more informations: series has reached 4 million , shard groups for telegraf: 205 telegraf one\_hour 2018-09-11T20:00:00Z 2018-09-11T21:00:00Z 2018-09-12T03:00:00Z 207 telegraf one\_hour 2018-09-11T21:00:00Z 2018-09-11T22:00:00Z 2018-09-12T04:00:00Z 209 telegraf one\_hour 2018-09-11T22:00:00Z 2018-09-11T23:00:00Z 2018-09-12T05:00:00Z 211 telegraf one\_hour 2018-09-11T23:00:00Z 2018-09-12T00:00:00Z 2018-09-12T06:00:00Z 213 telegraf one\_hour 2018-09-12T00:00:00Z 2018-09-12T01:00:00Z 2018-09-12T07:00:00Z 215 telegraf one\_hour 2018-09-12T01:00:00Z 2018-09-12T02:00:00Z 2018-09-12T08:00:00Z 217 telegraf one\_hour 2018-09-12T02:00:00Z 2018-09-12T03:00:00Z 2018-09-12T09:00:00Z 219 telegraf one\_hour 2018-09-12T03:00:00Z 2018-09-12T04:00:00Z 2018-09-12T10:00:00Z the retention policies: one\_hour 6h0m0s 1h0m0s 1 true tsm file: -rw-r–r-- 1 root root 390814115 9月 12 10:36 000000008-000000002.tsm -rw-r–r-- 1 root root 132929882 9月 12 10:41 000000009-000000001.tsm -rw-r–r-- 1 root root 132502656 9月 12 10:46 000000010-000000001.tsm -rw-r–r-- 1 root root 127318427 9月 12 10:52 000000011-000000001.tsm -rw-r–r-- 1 root root 391 9月 12 10:00 fields.idx influxdb config: [meta] dir = “/data/tdwadmin/tdwenv/influxdb/influxdb/var/lib/influxdb/meta” retention-autocreate = true [data] dir = “/data/tdwadmin/tdwenv/influxdb/influxdb/var/lib/influxdb/data” wal-dir = “/data/tdwadmin/tdwenv/influxdb/influxdb/var/lib/influxdb/wal” wal-fsync-delay = “0” index-version = “inmem” trace-logging-enabled = true query-log-enabled = false cache-max-memory-size = “20g” cache-snapshot-memory-size = “128m” max-index-log-file-size = “16m” max-series-per-database = 0 max-values-per-tag = 0 compact-full-write-cold-duration = “1h” cache-snapshot-write-cold-duration = “10m” max-concurrent-compactions = 4 [coordinator] write-timeout = “10s” [retention] enable = true check-intrerval = 30 [http] bind-address = “:8086” realm = “InfluxDB” log-enabled = false access-log-path = “influx.http.log” max-body-size = 0 and, yeah, the server has 128G RAM,48 Cores with a SSD of 256G. details showing at github issue: [Retention policy deletion check let the memory explode · Issue #10277 · influxdata/influxdb · GitHub](https://github.com/influxdata/influxdb/issues/10277)