Fix race condition by capturing version in goroutine#855
Merged
bharath-123 merged 3 commits intoflashbots:developfrom Nov 9, 2025
Merged
Fix race condition by capturing version in goroutine#855bharath-123 merged 3 commits intoflashbots:developfrom
bharath-123 merged 3 commits intoflashbots:developfrom
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When multiple relays are configured and some don't support getPayloadV2, a race condition occurs where one goroutine modifies the shared versionToUse variable, affecting response parsing in other concurrent goroutines. This causes valid V2 responses to be incorrectly parsed as V1, leading to decoding errors and potential missed slots. Fixed by capturing versionToUse in each goroutine's scope, ensuring each relay request maintains its own independent version state throughout the request-response lifecycle.
bharath-123
approved these changes
Nov 9, 2025
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The problem is related to a race condition when using the
versionToUsevariable in concurrent goroutines:Problem Description
At line 246 (
versionToUse = GetPayloadV1), a local variableversionToUseis modified, which is captured by the closure of all running goroutines (lines 159-314). This leads to the following issue:versionToUse == GetPayloadV2versionToUse = GetPayloadV1(line 246)StatusCode == 202 (Accepted)if versionToUse == GetPayloadV1(line 266)Technical Details
All goroutines share a single
versionToUsevariable captured through closure. When one goroutine modifies its value (line 246), it immediately affects the processing logic in other goroutines (lines 266-302), which may be at different execution stages.Consequences