docs_new/docs/references/environment_variables.mdx
SGLang supports various environment variables that can be used to configure its runtime behavior. This document provides a comprehensive list and aims to stay updated over time.
Note: The canonical prefix for all SGLang environment variables is SGLANG_. The legacy SGL_ prefix is deprecated: any SGL_* variable set in the environment is automatically rewritten to its SGLANG_* equivalent at import time with a deprecation warning, and the alias will be removed in a future release. A few variables keep an upstream/vendor prefix (e.g. MOONCAKE_*, ASCEND_*) because that is their canonical name.
These variables are primarily used for internal testing, continuous integration, or debugging.
<table style={{width: "100%", borderCollapse: "collapse", tableLayout: "fixed"}}> <colgroup> <col style={{width: "33.3%"}} /> <col style={{width: "33.3%"}} /> <col style={{width: "33.3%"}} /> </colgroup> <thead> <tr style={{borderBottom: "2px solid #d55816"}}> <th style={{textAlign: "left", padding: "10px 12px", fontWeight: 700, whiteSpace: "nowrap", backgroundColor: "rgba(255,255,255,0.02)"}}>Environment Variable</th> <th style={{textAlign: "left", padding: "10px 12px", fontWeight: 700, whiteSpace: "nowrap", backgroundColor: "rgba(255,255,255,0.05)"}}>Description</th> <th style={{textAlign: "left", padding: "10px 12px", fontWeight: 700, whiteSpace: "nowrap", backgroundColor: "rgba(255,255,255,0.02)"}}>Default Value</th> </tr> </thead> <tbody> <tr> <td style={{padding: "9px 12px", fontWeight: 500, backgroundColor: "rgba(255,255,255,0.02)"}}><code>SGLANG_IS_IN_CI</code></td> <td style={{padding: "9px 12px", backgroundColor: "rgba(255,255,255,0.05)"}}>Indicates if running in CI environment</td> <td style={{padding: "9px 12px", backgroundColor: "rgba(255,255,255,0.02)"}}><code>false</code></td> </tr> <tr> <td style={{padding: "9px 12px", fontWeight: 500, backgroundColor: "rgba(255,255,255,0.02)"}}><code>SGLANG_IS_IN_CI_AMD</code></td> <td style={{padding: "9px 12px", backgroundColor: "rgba(255,255,255,0.05)"}}>Indicates running in AMD CI environment</td> <td style={{padding: "9px 12px", backgroundColor: "rgba(255,255,255,0.02)"}}><code>false</code></td> </tr> <tr> <td style={{padding: "9px 12px", fontWeight: 500, backgroundColor: "rgba(255,255,255,0.02)"}}><code>SGLANG_TEST_RETRACT</code></td> <td style={{padding: "9px 12px", backgroundColor: "rgba(255,255,255,0.05)"}}>Enable retract decode testing</td> <td style={{padding: "9px 12px", backgroundColor: "rgba(255,255,255,0.02)"}}>`false`</td> </tr> <tr> <td style={{padding: "9px 12px", fontWeight: 500, backgroundColor: "rgba(255,255,255,0.02)"}}><code>SGLANG_TEST_RETRACT_NO_PREFILL_BS</code></td> <td style={{padding: "9px 12px", backgroundColor: "rgba(255,255,255,0.05)"}}>When SGLANG_TEST_RETRACT is enabled, no prefill is performed if the batch size exceeds SGLANG_TEST_RETRACT_NO_PREFILL_BS.</td> <td style={{padding: "9px 12px", backgroundColor: "rgba(255,255,255,0.02)"}}><code>2 ** 31</code></td> </tr> <tr> <td style={{padding: "9px 12px", fontWeight: 500, backgroundColor: "rgba(255,255,255,0.02)"}}><code>SGLANG_RECORD_STEP_TIME</code></td> <td style={{padding: "9px 12px", backgroundColor: "rgba(255,255,255,0.05)"}}>Record step time for profiling</td> <td style={{padding: "9px 12px", backgroundColor: "rgba(255,255,255,0.02)"}}>`false`</td> </tr> <tr> <td style={{padding: "9px 12px", fontWeight: 500, backgroundColor: "rgba(255,255,255,0.02)"}}><code>SGLANG_TEST_REQUEST_TIME_STATS</code></td> <td style={{padding: "9px 12px", backgroundColor: "rgba(255,255,255,0.05)"}}>Test request time statistics</td> <td style={{padding: "9px 12px", backgroundColor: "rgba(255,255,255,0.02)"}}>`false`</td> </tr> <tr> <td style={{padding: "9px 12px", fontWeight: 500, backgroundColor: "rgba(255,255,255,0.02)"}}><code>SGLANG_DEBUG_SYMM_MEM</code></td> <td style={{padding: "9px 12px", backgroundColor: "rgba(255,255,255,0.05)"}}>Enable debug checks that verify tensors passed to NCCL communication ops are allocated in the symmetric memory pool. Logs warnings (rank 0 only) with stack traces for any tensor not in the pool.</td> <td style={{padding: "9px 12px", backgroundColor: "rgba(255,255,255,0.02)"}}>`false`</td> </tr> <tr> <td style={{padding: "9px 12px", fontWeight: 500, backgroundColor: "rgba(255,255,255,0.02)"}}><code>SGLANG_KERNEL_API_LOGLEVEL</code></td> <td style={{padding: "9px 12px", backgroundColor: "rgba(255,255,255,0.05)"}}>Controls crash-debug kernel API logging. <code>0</code> disables logging, <code>1</code> logs API names, <code>3</code> logs tensor metadata, <code>5</code> adds tensor statistics, and <code>10</code> also writes pre-call dump snapshots.</td> <td style={{padding: "9px 12px", backgroundColor: "rgba(255,255,255,0.02)"}}><code>0</code></td> </tr> <tr> <td style={{padding: "9px 12px", fontWeight: 500, backgroundColor: "rgba(255,255,255,0.02)"}}><code>SGLANG_KERNEL_API_LOGDEST</code></td> <td style={{padding: "9px 12px", backgroundColor: "rgba(255,255,255,0.05)"}}>Destination for crash-debug kernel API logs. Use <code>stdout</code>, <code>stderr</code>, or a file path. <code>%i</code> is replaced with the process PID.</td> <td style={{padding: "9px 12px", backgroundColor: "rgba(255,255,255,0.02)"}}><code>stdout</code></td> </tr> <tr> <td style={{padding: "9px 12px", fontWeight: 500, backgroundColor: "rgba(255,255,255,0.02)"}}><code>SGLANG_KERNEL_API_DUMP_DIR</code></td> <td style={{padding: "9px 12px", backgroundColor: "rgba(255,255,255,0.05)"}}>Output directory for level-10 kernel API input/output dumps. <code>%i</code> is replaced with the process PID.</td> <td style={{padding: "9px 12px", backgroundColor: "rgba(255,255,255,0.02)"}}><code>sglang_kernel_api_dumps</code></td> </tr> <tr> <td style={{padding: "9px 12px", fontWeight: 500, backgroundColor: "rgba(255,255,255,0.02)"}}><code>SGLANG_KERNEL_API_DUMP_INCLUDE</code></td> <td style={{padding: "9px 12px", backgroundColor: "rgba(255,255,255,0.05)"}}>Comma-separated wildcard patterns for kernel API names to include in level-10 dumps.</td> <td style={{padding: "9px 12px", backgroundColor: "rgba(255,255,255,0.02)"}}>Not set</td> </tr> <tr> <td style={{padding: "9px 12px", fontWeight: 500, backgroundColor: "rgba(255,255,255,0.02)"}}><code>SGLANG_KERNEL_API_DUMP_EXCLUDE</code></td> <td style={{padding: "9px 12px", backgroundColor: "rgba(255,255,255,0.05)"}}>Comma-separated wildcard patterns for kernel API names to exclude from level-10 dumps.</td> <td style={{padding: "9px 12px", backgroundColor: "rgba(255,255,255,0.02)"}}>Not set</td> </tr> </tbody> </table>