Request body buffer not correctly cleared under heavy load

[alexus37]

Component(s)

router

Component version

v0.0.0-20240927172855-3e390cd5cf6c

wgc version

None

controlplane version

None

router version

v0.0.0-20240927172855-3e390cd5cf6c

What happened?

Description

We created a test script written in go that iterates for a list of test queries and uses go routines to make requests to the router which is running on the same machine. For some of the those requests this line raise the following graphQL error:

{"errors":[{"message":"error parsing request body: invalid character '{' after top-level value"}]}

when I look at the httpOperation.body I am seeing two post bodies inside eg.

"{\"query\": \"query {\\n  rateLimit {\\n    limit\\n    remaining\\n    resetAt\\n  }\\n}\"}{\"query\": \"query GetRepositoryMergeQueue {\\n  repository(owner: \\\"<REDACTED>\\\", name: \\\"<REDACTED>\\\") {\\n    mergeQueue {\\n      id\\n    }\\n  }\\n}\"}"

However, when I check what request is being received there is only 1 query in the body. It seems that the ReadBody function here is appending the new query to the buffer where the old query is already in. I am not sure if I need to start the router somehow differently or if I missed something else? When I do the requests sequentially I do not encounter this issue.

Steps to Reproduce

Create a script which uses go routines to target the router. I can pretty consistently reproduce it with 100 queries in total. The router fails on different queries so it seems there is some kind of race condition involved.

Expected Result

Have only the current post body in the buffer

Actual Result

The previous post body is still present in the buffer and the request fails.

Environment information

Environment

OS: (e.g., "Ubuntu 20.04")
Package Manager: pnpm, npm, yarn, etc
Compiler(if manually compiled): (e.g., "go 14.2")

Router configuration

version: "1"

dev_mode: true
listen_addr: 0.0.0.0:13002
execution_config:
  file:
    watch: true
    path: dev.supergraph.json

modules:
  custom-module-id:
    module-input-var: 2

# See https://cosmo-docs.wundergraph.com/router/proxy-capabilities#forward-http-headers-to-subgraphs
headers:
  all:
    request:
      - op: "propagate"
        named: Authorization

Router execution config

Log output

Additional context

We are only looking at query plans so all the requests are executed with these headers

{
  "X-WG-TRACE": "false",
  "X-WG-Skip-Loader": "true",
  "X-WG-Include-Query-Plan": "true",
}

[github-actions]

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[Noroth]

Hi @alexus37 thanks for submitting an issue.

This has been fixed in #1447, which is available in router version 0.152.1.