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| <h1 id="benchmarking-and-profiling"><a class="header" href="#benchmarking-and-profiling">Benchmarking and Profiling</a></h1> |
| <h2 id="internal-profiler"><a class="header" href="#internal-profiler">Internal profiler</a></h2> |
| <p>Cargo leverages <a href="https://crates.io/crates/tracing">tracing</a> |
| as a basic, hierarchical built-in profiler.</p> |
| <p>Environment variables:</p> |
| <ul> |
| <li><code>CARGO_LOG_PROFILE=<true|1></code>: log tracing events to a file in the current working directory</li> |
| <li><code>CARGO_LOG_PROFILE_CAPTURE_ARGS=<true|1></code>: include arguments in the events</li> |
| </ul> |
| <p>At process exit, your trace will be in a file like <code>trace-1668480819035032.json</code>. |
| Open that file with <a href="https://ui.perfetto.dev">ui.perfetto.dev</a> (or chrome://tracing) to browse your trace.</p> |
| <p>Example:</p> |
| <pre><code class="language-console">$ # Output first three levels of profiling info |
| $ CARGO_LOG_PROFILE=true cargo generate-lockfile |
| </code></pre> |
| <p><strong>Note:</strong> This is intended for the development of cargo and there are no compatibility guarantees on this functionality.</p> |
| <h2 id="benchmarking"><a class="header" href="#benchmarking">Benchmarking</a></h2> |
| <h3 id="benchsuite"><a class="header" href="#benchsuite">Benchsuite</a></h3> |
| <p>Head over to the <a href="https://github.com/rust-lang/cargo/tree/master/benches"><code>benches</code> |
| directory</a> for more |
| information about the benchmarking suite.</p> |
| <h3 id="informal-benchmarking"><a class="header" href="#informal-benchmarking">Informal benchmarking</a></h3> |
| <p>The overhead for starting a build should be kept as low as possible |
| (preferably, well under 0.5 seconds on most projects and systems). Currently, |
| the primary parts that affect this are:</p> |
| <ul> |
| <li>Running the resolver.</li> |
| <li>Querying the index.</li> |
| <li>Checking git dependencies.</li> |
| <li>Scanning the local project.</li> |
| <li>Building the unit dependency graph.</li> |
| </ul> |
| <p>One way to test this is to use <a href="https://github.com/sharkdp/hyperfine">hyperfine</a>. This is a tool that can be used to |
| measure the difference between different commands and settings. Usually this |
| is done by measuring the time it takes for <code>cargo build</code> to finish in a large |
| project where the build is fresh (no actual compilation is performed). Just |
| run <code>cargo build</code> once before using hyperfine.</p> |
| |
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