InfluxDB not releasing memory

I was backfilling 2 months of data using a python script to influxdb. In the middle of doing this data disk (/var/lib/influxdb) got full so influx started writing to RAM and eventually it also got full.

To make things normal I’ve deleted some of the unused files to make free space. So ideally influx should have written all data from RAM to disk because now disk space is available. But it’s not releasing data from RAM.

I know, I can restart influxdb and things will be back to normal, but is there any recommended way to handle this type of situation without restarting influxdb.

Server configuration (Ubuntu Server 16.04)

H/W path    Device       Class      Description
                         system     HVM domU
/0                       bus        Motherboard
/0/0                     memory     96KiB BIOS
/0/401                   processor  Intel(R) Xeon(R) CPU E5-2686 v4 @ 2.30GHz
/0/402                   processor  CPU
/0/403                   processor  CPU
/0/404                   processor  CPU
/0/1000                  memory     16GiB System Memory
/0/1000/0                memory     16GiB DIMM RAM
/0/100                   bridge     440FX - 82441FX PMC [Natoma]
/0/100/1                 bridge     82371SB PIIX3 ISA [Natoma/Triton II]
/0/100/1.1               storage    82371SB PIIX3 IDE [Natoma/Triton II]
/0/100/1.3               bridge     82371AB/EB/MB PIIX4 ACPI
/0/100/2                 display    GD 5446
/0/100/3    ens3         network    82599 Ethernet Controller Virtual Function
/0/100/1f                generic    Xen Platform Device
/1          veth79e1322  network    Ethernet interface

Influx version is 1.6.0

I don’t know the good sollution for your problem yet. But I suggest you to set up the cache-max-memory-size parameter in influxdb.conf file to prevent to run out of memory. After InfluxDB reac this value it will be reject the writing.