MongoDB: Mongoimport server selection error , connection refused, too many files open

Question

Trying to insert several JSON files to MongoDB collections using shell script as following,

#!/bin/bash
NUM=50000
for ((i=o;i<NUM;i++))
do
 mongoimport --host localhost --port 27018 -u 'admin' -p 'password' --authenticationDatabase 'admin' -d random_test -c tri_${i} /home/test/json_files/json_${i}.csv --jsonArray
done 

after several successful adding, these errors were shown on terminal

Failed: connection(localhost:27017[-3]), incomplete read of message header: EOF
error connecting to host: could not connect to server: 
server selection error: server selection timeout, 
current topology: { Type: Single, Servers: 
[{ Addr: localhost:27017, Type: Unknown, 
State: Connected, Average RTT: 0, Last error: connection() : 
dial tcp [::1]:27017: connect: connection refused }, ] }

And below the eoor messages from mongo.log, that said too many open files, can I somehow limit the thread number? or what should I do to fix it?? Thanks a lot!

2020年07月21日T11:13:33.613+0200 E STORAGE [conn971] WiredTiger error (24) [1595322813:613873][53971:0x7f7c8d228700], WT_SESSION.create: __posix_directory_sync, 151: /home/mongodb/bin/data/db/index-969--7295385362343345274.wt: directory-sync: Too many open files Raw: [1595322813:613873][53971:0x7f7c8d228700], WT_SESSION.create: __posix_directory_sync, 151: /home/mongodb/bin/data/db/index-969--7295385362343345274.wt: directory-sync: Too many open files
2020年07月21日T11:13:33.613+0200 E STORAGE [conn971] WiredTiger error (-31804) [1595322813:613892][53971:0x7f7c8d228700], WT_SESSION.create: __wt_panic, 490: the process must exit and restart: WT_PANIC: WiredTiger library panic Raw: [1595322813:613892][53971:0x7f7c8d228700], WT_SESSION.create: __wt_panic, 490: the process must exit and restart: WT_PANIC: WiredTiger library panic
2020年07月21日T11:13:33.613+0200 F - [conn971] Fatal Assertion 50853 at src/mongo/db/storage/wiredtiger/wiredtiger_util.cpp 414
2020年07月21日T11:13:33.613+0200 F - [conn971]
***aborting after fassert() failure

Answer 1

Depending on your OS, there's multiple ways to modify the maxopenfile of MongoDB.
On Debian and Ubuntu, in /lib/systemd/system/mongod.service there's the LimitNOFILE argument which can be increased if needed.

You have more infos on other OS on https://docs.mongodb.com/manual/reference/ulimit/

• Erwin Zangwill: I am using redhat, but I don't have the root permission. Can I some how shut down a file once its importing is done?
• bebu: Without the root or sudo permission I don't think you'll be able to change the ulimit either on the OS or the daemon's side unfortunately. All the open files are managed by the mongod process, it's likely it's opening creating files while importinng your data. Have you tried limiting your NUM variable to a much lower value?