LATENCY

Note: Not yet supported

The LATENCY command in DiceDB is used to measure and analyze the latency of various operations within the DiceDB server. This command provides insights into the performance and responsiveness of the DiceDB instance, helping administrators to identify and troubleshoot latency issues.

Command Syntax

LATENCY [SUBCOMMAND] [ARGUMENTS]

Parameters

Parameter	Subcommand	Description	Return Type	Required
SUBCOMMAND		Specifies the operation to perform. Available subcommands are:	String	Yes
	LATEST	Returns the latest latency spikes.	Array	Yes
	HISTORY	Returns the latency history for a specific event.	Array	Yes
	RESET	Resets the latency data for specific events or all events.	Integer	Yes
	GRAPH	Returns a latency graph for a specific event.	String	Yes
	DOCTOR	Provides a human-readable report of latency issues.	String	Yes
ARGUMENTS	N/A	Additional arguments required by certain subcommands (if applicable).	Varies	No

Return Values

Condition	Return Value
LATEST	Array of latency spikes
HISTORY	Array of latency samples (timestamp, latency)
RESET	Integer (number of events reset)
GRAPH	String (graph representing latency data)
DOCTOR	String (detailed report with suggestions)
Syntax or specified constraints are invalid	error

Behaviour

When the LATENCY command is executed, it performs the specified subcommand operation. The behavior varies based on the subcommand:

• LATEST: Fetches and returns the most recent latency spikes recorded by the DiceDB server.
• HISTORY: Retrieves the historical latency data for a specified event, allowing for analysis of latency trends over time.
• RESET: Clears the latency data for specified events or all events, effectively resetting the latency monitoring.
• GRAPH: Generates and returns a visual representation of the latency data for a specified event.
• DOCTOR: Analyzes the latency data and provides a human-readable report with potential causes and suggestions for mitigation.

Errors

• Invalid Subcommand:

  • Error Message: ERR unknown subcommand 'subcommand'
  • If an unrecognized subcommand is provided, DiceDB will return an error.

• Missing Arguments:

  • Error Message: ERR wrong number of arguments for 'latency subcommand' command
  • If required arguments for a subcommand are missing, DiceDB will return an error.

• Invalid Event Name:

  • Error Message: ERR no such event 'event_name'
  • If an invalid event name is provided for subcommands like HISTORY, RESET, or GRAPH, DiceDB will return an error.

Example Usage

LATEST Subcommand

Fetches the latest latency spikes recorded by the DiceDB server.

127.0.0.1:7379> LATENCY LATEST
1) 1) "command"
   2) (integer) 1633024800
   3) (integer) 15
2) 1) "fork"
   2) (integer) 1633024805
   3) (integer) 25

HISTORY Subcommand

Retrieves the historical latency data for the command event.

127.0.0.1:7379> LATENCY HISTORY command
1) 1) (integer) 1633024800
   2) (integer) 15
2) 1) (integer) 1633024805
   2) (integer) 25

RESET Subcommand

Resets the latency data for the command event.

127.0.0.1:7379> LATENCY RESET command
(integer) 1

GRAPH Subcommand

Generates a visual representation of the latency data for the command event.

127.0.0.1:7379> LATENCY GRAPH command
| 15 | 25 |

DOCTOR Subcommand

Provides a human-readable report of latency issues.

127.0.0.1:7379> LATENCY DOCTOR
Latency Doctor Report:
- Command latency spikes detected. Consider optimizing your commands.
- Fork latency spikes detected. Check your system's I/O performance.