fatal error: concurrent map read and map write - in internal/output.(*prefixWriter).writeLine

[tinmrn]

• Task version: v3.40.0 (h1:1gKx+2UDz06Jtm0MBiN+EqVN87wWEyspuEze4LRGusk=)
• Operating system: Linux 5.10.0-33-amd64 SMP Debian 5.10.226-1 (2024-10-03) x86_64 GNU/Linux
• Experiments enabled: don't think so

fatal error: concurrent map read and map write

goroutine 67 [running]:
github.com/go-task/task/v3/internal/output.(*prefixWriter).writeLine(0xc0004ca1e0, {0xc0006054c8, 0x2})
	github.com/go-task/task/v3@v3.40.0/internal/output/prefixed.go:88 +0xc5
github.com/go-task/task/v3/internal/output.(*prefixWriter).writeOutputLines(0xc0004ca1e0, 0x0)
	github.com/go-task/task/v3@v3.40.0/internal/output/prefixed.go:58 +0x6b
github.com/go-task/task/v3/internal/output.(*prefixWriter).Write(0xc0004ca1e0, {0xc0006d8000?, 0x418b9f?, 0xc0002ee010?})
	github.com/go-task/task/v3@v3.40.0/internal/output/prefixed.go:47 +0x45
io.copyBuffer({0xef22a0, 0xc0004ca1e0}, {0xef1840, 0xc0002ee010}, {0x0, 0x0, 0x0})
	io/io.go:431 +0x1de

this taskfile reproduces it pretty consistently:

version: '3'

output: prefixed

tasks:

  do-all:
    deps:
      - task-1
      - task-2
      - task-3
      - task-4
      - task-5
      - task-6
      - task-7
      - task-8
      - task-9
      - task-10
      - task-11
      - task-12
      - task-13
      - task-14
      - task-15
      - task-16
      - task-17
      - task-18
      - task-19
      - task-20

  task-1:
    cmds:
      - yes

  task-2:
    cmds:
      - yes

  task-3:
    cmds:
      - yes

  task-4:
    cmds:
      - yes

  task-5:
    cmds:
      - yes

  task-6:
    cmds:
      - yes

  task-7:
    cmds:
      - yes

  task-8:
    cmds:
      - yes

  task-9:
    cmds:
      - yes

  task-10:
    cmds:
      - yes

  task-11:
    cmds:
      - yes

  task-12:
    cmds:
      - yes

  task-13:
    cmds:
      - yes

  task-14:
    cmds:
      - yes

  task-15:
    cmds:
      - yes

  task-16:
    cmds:
      - yes

  task-17:
    cmds:
      - yes

  task-18:
    cmds:
      - yes

  task-19:
    cmds:
      - yes

  task-20:
    cmds:
      - yes

when run like so:

task do-all > /dev/null

^ The dev/null redirect gives a higher chance of triggering the concurrency conflict, i think because it allows for higher throughput than outputting to a terminal. But this bug occurs in our CI every now and then, too.

i also attach a bunch of error outputs just in case:

err-1.txt
err-2.txt
err-3.txt
err-4.txt
err-5.txt
err-6.txt
err-7.txt
err-8.txt
err-9.txt

[vmaerten]

Fixed in #1974