MongoDB consume more CPU and memory

KRISHNAKUMAR_K · September 1, 2023, 5:48am

Hi Team,

I have hosted my database in AWS EC2 (ubuntu) server,I am facing Slowness in my database and server consume more CPU and memory, What is the cause? Is this query related issue? How to fix this issue.

Thanks,
Krishnakumar K

KRISHNAKUMAR_K · September 1, 2023, 5:58am

Below is the logs.

`
{"t":{"$date":"2023-08-31T12:31:21.089+00:00"},"s":"I",  "c":"CONTROL",  "id":20698,   "ctx":"-","msg":"***** SERVER RESTARTED *****"}
{"t":{"$date":"2023-08-31T12:31:21.090+00:00"},"s":"I",  "c":"NETWORK",  "id":4915701, "ctx":"-","msg":"Initialized wire specification","attr":{"spec":{"incomingExternalClient":{"minWireVersion":0,"maxWireVersion":17},"incomingInternalClient":{"minWireVersion":0,"maxWireVersion":17},"outgoing":{"minWireVersion":6,"maxWireVersion":17},"isInternalClient":true}}}
{"t":{"$date":"2023-08-31T12:31:21.093+00:00"},"s":"I",  "c":"CONTROL",  "id":23285,   "ctx":"main","msg":"Automatically disabling TLS 1.0, to force-enable TLS 1.0 specify --sslDisabledProtocols 'none'"}
{"t":{"$date":"2023-08-31T12:31:21.093+00:00"},"s":"I",  "c":"NETWORK",  "id":4648601, "ctx":"main","msg":"Implicit TCP FastOpen unavailable. If TCP FastOpen is required, set tcpFastOpenServer, tcpFastOpenClient, and tcpFastOpenQueueSize."}
{"t":{"$date":"2023-08-31T12:31:21.297+00:00"},"s":"I",  "c":"REPL",     "id":5123008, "ctx":"main","msg":"Successfully registered PrimaryOnlyService","attr":{"service":"TenantMigrationDonorService","namespace":"config.tenantMigrationDonors"}}
{"t":{"$date":"2023-08-31T12:31:21.297+00:00"},"s":"I",  "c":"REPL",     "id":5123008, "ctx":"main","msg":"Successfully registered PrimaryOnlyService","attr":{"service":"TenantMigrationRecipientService","namespace":"config.tenantMigrationRecipients"}}
{"t":{"$date":"2023-08-31T12:31:21.297+00:00"},"s":"I",  "c":"REPL",     "id":5123008, "ctx":"main","msg":"Successfully registered PrimaryOnlyService","attr":{"service":"ShardSplitDonorService","namespace":"config.tenantSplitDonors"}}
{"t":{"$date":"2023-08-31T12:31:21.297+00:00"},"s":"I",  "c":"CONTROL",  "id":5945603, "ctx":"main","msg":"Multi threading initialized"}
{"t":{"$date":"2023-08-31T12:31:21.297+00:00"},"s":"I",  "c":"CONTROL",  "id":4615611, "ctx":"initandlisten","msg":"MongoDB starting","attr":{"pid":5492,"port":21497,"dbPath":"/var/lib/mongodb","architecture":"64-bit","host":"ip-192-168-3-34"}}
{"t":{"$date":"2023-08-31T12:31:21.297+00:00"},"s":"I",  "c":"CONTROL",  "id":23403,   "ctx":"initandlisten","msg":"Build Info","attr":{"buildInfo":{"version":"6.0.6","gitVersion":"26b4851a412cc8b9b4a18cdb6cd0f9f642e06aa7","openSSLVersion":"OpenSSL 1.1.1f  31 Mar 2020","modules":[],"allocator":"tcmalloc","environment":{"distmod":"ubuntu2004","distarch":"x86_64","target_arch":"x86_64"}}}}
{"t":{"$date":"2023-08-31T12:31:21.297+00:00"},"s":"I",  "c":"CONTROL",  "id":51765,   "ctx":"initandlisten","msg":"Operating System","attr":{"os":{"name":"Ubuntu","version":"22.04"}}}
{"t":{"$date":"2023-08-31T12:31:21.297+00:00"},"s":"I",  "c":"CONTROL",  "id":21951,   "ctx":"initandlisten","msg":"Options set by command line","attr":{"options":{"config":"/etc/mongod.conf","net":{"bindIp":"0.0.0.0","port":21497},"processManagement":{"timeZoneInfo":"/usr/share/zoneinfo"},"security":{"authorization":"enabled"},"storage":{"dbPath":"/var/lib/mongodb"},"systemLog":{"destination":"file","logAppend":true,"path":"/var/log/mongodb/mongod.log"}}}}
{"t":{"$date":"2023-08-31T12:31:21.298+00:00"},"s":"I",  "c":"STORAGE",  "id":22270,   "ctx":"initandlisten","msg":"Storage engine to use detected by data files","attr":{"dbpath":"/var/lib/mongodb","storageEngine":"wiredTiger"}}
{"t":{"$date":"2023-08-31T12:31:21.298+00:00"},"s":"I",  "c":"STORAGE",  "id":22297,   "ctx":"initandlisten","msg":"Using the XFS filesystem is strongly recommended with the WiredTiger storage engine. See http://dochub.mongodb.org/core/prodnotes-filesystem","tags":["startupWarnings"]}
{"t":{"$date":"2023-08-31T12:31:21.298+00:00"},"s":"I",  "c":"STORAGE",  "id":22315,   "ctx":"initandlisten","msg":"Opening WiredTiger","attr":{"config":"create,cache_size=15217M,session_max=33000,eviction=(threads_min=4,threads_max=4),config_base=false,statistics=(fast),log=(enabled=true,remove=true,path=journal,compressor=snappy),builtin_extension_config=(zstd=(compression_level=6)),file_manager=(close_idle_time=600,close_scan_interval=10,close_handle_minimum=2000),statistics_log=(wait=0),json_output=(error,message),verbose=[recovery_progress:1,checkpoint_progress:1,compact_progress:1,backup:0,checkpoint:0,compact:0,evict:0,history_store:0,recovery:0,rts:0,salvage:0,tiered:0,timestamp:0,transaction:0,verify:0,log:0],"}}
{"t":{"$date":"2023-08-31T12:31:22.613+00:00"},"s":"I",  "c":"STORAGE",  "id":4795906, "ctx":"initandlisten","msg":"WiredTiger opened","attr":{"durationMillis":1315}}
{"t":{"$date":"2023-08-31T12:31:22.613+00:00"},"s":"I",  "c":"RECOVERY", "id":23987,   "ctx":"initandlisten","msg":"WiredTiger recoveryTimestamp","attr":{"recoveryTimestamp":{"$timestamp":{"t":0,"i":0}}}}
{"t":{"$date":"2023-08-31T12:31:22.660+00:00"},"s":"W",  "c":"CONTROL",  "id":5123300, "ctx":"initandlisten","msg":"vm.max_map_count is too low","attr":{"currentValue":65530,"recommendedMinimum":102400,"maxConns":51200},"tags":["startupWarnings"]}
{"t":{"$date":"2023-08-31T12:31:22.665+00:00"},"s":"I",  "c":"NETWORK",  "id":4915702, "ctx":"initandlisten","msg":"Updated wire specification","attr":{"oldSpec":{"incomingExternalClient":{"minWireVersion":0,"maxWireVersion":17},"incomingInternalClient":{"minWireVersion":0,"maxWireVersion":17},"outgoing":{"minWireVersion":6,"maxWireVersion":17},"isInternalClient":true},"newSpec":{"incomingExternalClient":{"minWireVersion":0,"maxWireVersion":17},"incomingInternalClient":{"minWireVersion":17,"maxWireVersion":17},"outgoing":{"minWireVersion":17,"maxWireVersion":17},"isInternalClient":true}}}
{"t":{"$date":"2023-08-31T12:31:22.665+00:00"},"s":"I",  "c":"REPL",     "id":5853300, "ctx":"initandlisten","msg":"current featureCompatibilityVersion value","attr":{"featureCompatibilityVersion":"6.0","context":"startup"}}
{"t":{"$date":"2023-08-31T12:31:22.667+00:00"},"s":"I",  "c":"STORAGE",  "id":5071100, "ctx":"initandlisten","msg":"Clearing temp directory"}
{"t":{"$date":"2023-08-31T12:31:22.940+00:00"},"s":"I",  "c":"CONTROL",  "id":20536,   "ctx":"initandlisten","msg":"Flow Control is enabled on this deployment"}
{"t":{"$date":"2023-08-31T12:31:22.940+00:00"},"s":"I",  "c":"FTDC",     "id":20625,   "ctx":"initandlisten","msg":"Initializing full-time diagnostic data capture","attr":{"dataDirectory":"/var/lib/mongodb/diagnostic.data"}}
{"t":{"$date":"2023-08-31T12:31:22.944+00:00"},"s":"I",  "c":"REPL",     "id":6015317, "ctx":"initandlisten","msg":"Setting new configuration state","attr":{"newState":"ConfigReplicationDisabled","oldState":"ConfigPreStart"}}
{"t":{"$date":"2023-08-31T12:31:22.944+00:00"},"s":"I",  "c":"STORAGE",  "id":22262,   "ctx":"initandlisten","msg":"Timestamp monitor starting"}
{"t":{"$date":"2023-08-31T12:31:22.946+00:00"},"s":"I",  "c":"NETWORK",  "id":23015,   "ctx":"listener","msg":"Listening on","attr":{"address":"/tmp/mongodb-21497.sock"}}
{"t":{"$date":"2023-08-31T12:31:22.946+00:00"},"s":"I",  "c":"NETWORK",  "id":23015,   "ctx":"listener","msg":"Listening on","attr":{"address":"0.0.0.0"}}
{"t":{"$date":"2023-08-31T12:31:22.946+00:00"},"s":"I",  "c":"NETWORK",  "id":23016,   "ctx":"listener","msg":"Waiting for connections","attr":{"port":21497,"ssl":"off"}}
{"t":{"$date":"2023-08-31T12:31:45.891+00:00"},"s":"I",  "c":"NETWORK",  "id":22943,   "ctx":"listener","msg":"Connection accepted","attr":{"remote":"192.168.3.34:34430","uuid":"8e9deb4f-1628-4c71-9f53-c893b9da16e9","connectionId":1,"connectionCount":1}}
{"t":{"$date":"2023-08-31T12:31:45.908+00:00"},"s":"I",  "c":"NETWORK",  "id":51800,   "ctx":"conn1","msg":"client metadata","attr":{"remote":"192.168.3.34:34430","client":"conn1","doc":{"driver":{"name":"nodejs|Mongoose","version":"4.16.0|6.11.1"},"platform":"Node.js v18.0.0, LE","os":{"name":"linux","architecture":"x64","version":"5.19.0-1028-aws","type":"Linux"}}}}
{"t":{"$date":"2023-08-31T12:31:45.982+00:00"},"s":"I",  "c":"NETWORK",  "id":22943,   "ctx":"listener","msg":"Connection accepted","attr":{"remote":"192.168.3.34:34440","uuid":"e6c8afba-29f8-49c1-b3ff-940cb98477ea","connectionId":2,"connectionCount":2}}
{"t":{"$date":"2023-08-31T12:31:46.032+00:00"},"s":"I",  "c":"NETWORK",  "id":51800,   "ctx":"conn2","msg":"client metadata","attr":{"remote":"192.168.3.34:34440","client":"conn2","doc":{"driver":{"name":"nodejs|Mongoose","version":"4.16.0|6.11.1"},"platform":"Node.js v18.0.0, LE","os":{"name":"linux","architecture":"x64","version":"5.19.0-1028-aws","type":"Linux"}}}}
{"t":{"$date":"2023-08-31T12:31:46.034+00:00"},"s":"I",  "c":"NETWORK",  "id":22943,   "ctx":"listener","msg":"Connection accepted","attr":{"remote":"192.168.3.34:34446","uuid":"4ad51d65-c201-4cc6-a39a-c56ea21b0cc1","connectionId":3,"connectionCount":3}}`

Aasawari · September 7, 2023, 3:53am

Hi @KRISHNAKUMAR_K and welcome to MongoDB community forums!!

MongoDB is designed to use memory for caching frequently accessed data, so it’s generally expected that memory usage is higher than CPU usage. In saying so, there could be multiple reasons on why you are seeing this:

Are you performing any complex queries on the collection? The queries that involve aggregations, sorting, or complex filtering may result into significant CPU power to process.
Are the indexes properly defined and are the aggregation queries utilising the indexes?
You can check how much work the MongoDB server is doing by using mongostat command. If the output of mongostat indicates a heavily loaded server, you might need to increase the RAM of the server. If your server doesn’t have enough RAM to accommodate your working set (the data and indexes that are actively used), MongoDB may rely more on CPU processing to fetch and process data from disk.
Are there multiple concurrent writes happening in the collections ?

Please feel free to reach out in sace of any queries.

Warm Regards
Aasawari