How to use the command pprof (with examples)

The pprof command is a powerful command-line tool that allows you to visualize and analyze profile data. It is commonly used for profiling Go programs, but it can also be used for other languages. With pprof, you can generate text reports, graphs, and even run a web server with a web interface for profile analysis.

Use case 1: Generate a text report from a specific profiling file

Code:

pprof -top ./fibbo ./fibbo-profile.pb.gz

Motivation: Generating a text report is useful when you want to quickly get an overview of the performance of your program. This can help identify bottlenecks or areas for optimization.

Explanation:

• -top: This option specifies that we want to generate a top text report, which displays the top functions sorted by their total time spent in the CPU.
• ./fibbo: This is the binary file that you want to profile.
• ./fibbo-profile.pb.gz: This is the profiling file that contains the information about the program’s execution. It has a .pb.gz extension.

Example output:

Showing nodes accounting for 100% of 10.10s total
Dropped 171 nodes (cum <= 0.05s)
Showing top 10 nodes out of 26 (cum >= 0.50s)
      flat  flat%   sum%        cum   cum%
     4.02s 40.10% 40.10%      4.02s 40.10%  main.fib
     3.01s 29.90% 70.00%      3.71s 36.73%  main.main
     1.00s  9.90% 79.90%      1.70s 16.83%  main.init
     0.50s  4.95% 84.85%      0.50s  4.95%  main.fib.func1
     0.50s  4.95% 89.80%     10.00s 99.01%  runtime.goexit
     0.50s  4.95% 94.75%      1.18s 11.68%  runtime.main
     0.50s  4.95% 99.70%      0.60s  5.94%  runtime.gopark
     0.00s  0.00% 99.70%      0.50s  4.95%  runtime.gosched
     0.00s  0.00% 99.70%      1.19s 11.79%  runtime.newstack
     0.00s  0.00% 99.70%      0.60s  5.94%  runtime.mstart

Use case 2: Generate a graph and open it in a web browser

Code:

pprof -svg ./fibbo ./fibbo-profile.pb.gz

Motivation: Generating a graph can provide a more visual representation of the profiling data, making it easier to identify performance issues or patterns in the program’s execution.

Explanation:

• -svg: This option specifies that we want to generate an SVG graph. SVG (Scalable Vector Graphics) is a format that can be easily opened and viewed in web browsers.
• ./fibbo: This is the binary file that you want to profile.
• ./fibbo-profile.pb.gz: This is the profiling file that contains the information about the program’s execution. It has a .pb.gz extension.

Example output: The pprof command will generate an SVG graph file, and depending on your system configuration, it will either open the file in your default web browser or provide you with the path to the generated file.

Use case 3: Run pprof in interactive mode

Code:

pprof ./fibbo ./fibbo-profile.pb.gz

Motivation: Running pprof in interactive mode allows you to perform analysis on the profiling data in a more exploratory manner. You can navigate through the different functions, view their profiles, and analyze the data interactively.

Explanation:

• ./fibbo: This is the binary file that you want to profile.
• ./fibbo-profile.pb.gz: This is the profiling file that contains the information about the program’s execution. It has a .pb.gz extension.

Example output: Running the pprof command in interactive mode will launch a command-line interface where you can interactively analyze the profiling data. It will show you different commands and options that you can use to navigate and explore the data.

Use case 4: Run a web server with a web interface

Code:

pprof -http=localhost:8080 ./fibbo ./fibbo-profile.pb.gz

Motivation: Running a web server with a web interface allows you to access and analyze the profiling data using a web browser. This can be useful when you want to share the analysis with others or when you prefer a visual and interactive interface.

Explanation:

• -http=localhost:8080: This option instructs pprof to run a web server with the specified host and port. Here, we are using localhost as the host and 8080 as the port.
• ./fibbo: This is the binary file that you want to profile.
• ./fibbo-profile.pb.gz: This is the profiling file that contains the information about the program’s execution. It has a .pb.gz extension.

Example output: The pprof command will start a web server and provide you with a URL (e.g., http://localhost:8080). You can open this URL in a web browser to access the web interface, where you can analyze the profiling data.

Use case 5: Fetch a profile from an HTTP server and generate a report

Code:

pprof http://localhost:8080/debug/pprof

Motivation: Fetching a profile from an HTTP server allows you to analyze the profiling data of a remote program. This can be useful when you want to analyze performance issues in production environments or when you need to share the profiling data with someone who doesn’t have direct access to the program.

Explanation:

• http://localhost:8080/debug/pprof: This is the URL of the HTTP server where the profiling data can be accessed. In this example, it is assumed that the program is running on localhost and exposing the profiling data at the /debug/pprof endpoint.

Example output: The pprof command will fetch the profiling data from the specified URL and generate a report based on it. The output can vary depending on the specific data returned by the HTTP server. It will be similar to the text or graph reports generated in the previous examples, but the data will be obtained remotely.