# MONITOR `MONITOR` is a debugging command that streams back every command processed by the Redis server. It can help in understanding what is happening to the database. This command can both be used via `redis-cli` and via `telnet`. The ability to see all the requests processed by the server is useful in order to spot bugs in an application both when using Redis as a database and as a distributed caching system. ``` $ redis-cli monitor 1339518083.107412 [0 127.0.0.1:60866] "keys" "*" 1339518087.877697 [0 127.0.0.1:60866] "dbsize" 1339518090.420270 [0 127.0.0.1:60866] "set" "x" "6" 1339518096.506257 [0 127.0.0.1:60866] "get" "x" 1339518099.363765 [0 127.0.0.1:60866] "eval" "return redis.call('set','x','7')" "0" 1339518100.363799 [0 lua] "set" "x" "7" 1339518100.544926 [0 127.0.0.1:60866] "del" "x" ``` Use `SIGINT` (Ctrl-C) to stop a `MONITOR` stream running via `redis-cli`. ``` $ telnet localhost 6379 Trying 127.0.0.1... Connected to localhost. Escape character is '^]'. MONITOR +OK +1339518083.107412 [0 127.0.0.1:60866] "keys" "*" +1339518087.877697 [0 127.0.0.1:60866] "dbsize" +1339518090.420270 [0 127.0.0.1:60866] "set" "x" "6" +1339518096.506257 [0 127.0.0.1:60866] "get" "x" +1339518099.363765 [0 127.0.0.1:60866] "del" "x" +1339518100.544926 [0 127.0.0.1:60866] "get" "x" QUIT +OK Connection closed by foreign host. ``` Manually issue the [`QUIT`](https://redis.io/docs/latest/commands/quit) or [`RESET`](https://redis.io/docs/latest/commands/reset) commands to stop a `MONITOR` stream running via `telnet`. ## Commands not logged by MONITOR Because of security concerns, no administrative commands are logged by `MONITOR`'s output and sensitive data is redacted in the command [`AUTH`](https://redis.io/docs/latest/commands/auth). Furthermore, the command [`QUIT`](https://redis.io/docs/latest/commands/quit) is also not logged. ## Cost of running MONITOR Because `MONITOR` streams back **all** commands, its use comes at a cost. The following (totally unscientific) benchmark numbers illustrate what the cost of running `MONITOR` can be. Benchmark result **without** `MONITOR` running: ``` $ src/redis-benchmark -c 10 -n 100000 -q PING_INLINE: 101936.80 requests per second PING_BULK: 102880.66 requests per second SET: 95419.85 requests per second GET: 104275.29 requests per second INCR: 93283.58 requests per second ``` Benchmark result **with** `MONITOR` running (`redis-cli monitor > /dev/null`): ``` $ src/redis-benchmark -c 10 -n 100000 -q PING_INLINE: 58479.53 requests per second PING_BULK: 59136.61 requests per second SET: 41823.50 requests per second GET: 45330.91 requests per second INCR: 41771.09 requests per second ``` In this particular case, running a single `MONITOR` client can reduce the throughput by more than 50%. Running more `MONITOR` clients will reduce throughput even more. ## Behavior change history * `>= 6.0.0`: [`AUTH`](https://redis.io/docs/latest/commands/auth) excluded from the command's output. * `>= 6.2.0`: "[`RESET`](https://redis.io/docs/latest/commands/reset) can be called to exit monitor mode. * `>= 6.2.4`: "[`AUTH`](https://redis.io/docs/latest/commands/auth), [`HELLO`](https://redis.io/docs/latest/commands/hello), [`EVAL`](https://redis.io/docs/latest/commands/eval), [`EVAL_RO`](https://redis.io/docs/latest/commands/eval_ro), [`EVALSHA`](https://redis.io/docs/latest/commands/evalsha) and [`EVALSHA_RO`](https://redis.io/docs/latest/commands/evalsha_ro) included in the command's output. ## Return information {{< multitabs id="monitor-return-info" tab1="RESP2" tab2="RESP3" >}} **Non-standard return value**. Dumps the received commands in an infinite flow. -tab-sep- **Non-standard return value**. Dumps the received commands in an infinite flow.