perf_hooks.monitorEventLoopDelay([options]) function in Node.js

In Node. js, the "perf_hooks.monitorEventLoopDelay([options])'' is a special-purpose function that enables the assessment of the event loop efficiency, which is the principal method that handles all asynchronous process execution. It helps to maintain the non-blocking I/O operations, like reading files, handling of network requests, and timer also.

However, when the event loop becomes overloaded with operations, its efficiency can degrade, leading to slower processing and potential bottlenecks in handling asynchronous tasks.

The "monitorEventLoopDelay()" function helps determine the latency of the event loop commonly referred to as the event loop delay that enables users to know instances where the event loop has very high latencies that might be an indication of system load, competition of resources, and inefficiencies in the code.

This function is the existing function returning a Histogram object to track event loop delay over time, which comes with statistic information like minimum, maximum, mean, and standard deviation of delays present within the program. Using the 'resolution' option, developers can also set a sampling rate which defines how often the delay is going to be measured.

To achieve these, the developers can use "monitorEventLoopDelay()" to detect performance problems, improve application performance, and guarantee that the application executes as referred to when dealing with environments that require handling a large number of asynchronous tasks..

Approach 1: Basic Monitoring for Diagnostics

The following is the simplest form of Basic Monitoring for Diagnostics called monitorEventLoopDelay(), where the extent of the delay in the event loop is periodically measured and information recorded. This a very basic approach that is suitable for lightweight applications, which require real-time monitoring of the event loop to determine whether there is a backlog in the processing of tasks.

Example:

Let us take an example to illustrate the perf_hooks.monitorEventLoopDelay([options]) function in Node.js.

Output:

 Event Loop Delay Diagnostics (Logged at 2024-09-11T09:16:37.473Z): Minimum delay: 10043392 ms Maximum delay: 76283903 ms Mean delay : 11315496.542986425 ms Standard deviation: 6149236.318436448 ms 50th percentile: 10108927 ms 95th percentile: 13606911 ms 99th percentile: 46825471 ms Event loop delay data logged successfully. 

Explanation:

In this example, the provided code uses the ''perf_hooks.monitorEventLoopDelay()'' method to continuously check the delay in the event loop and log this data. It starts a monitor with a 10ms resolution to track delays and records such basic statistics as min, max, average delay, and percentiles with 5-second intervals. This Log data is printed both on the console and file named "event_loop_delay_logs. Txt". It is important to know that monitoring stops after 1 minute by itself. Here, shutdown is managed with the help of some signals, that as 'SIGINT' and 'SIGTERM'. For example, the code is useful for routine performance degradation analysis since, when profiling the event loop, it is possible to recognize inefficiencies in real-time.