fix(session): race conditions in unit tests

[gyuho]

Fix

=== NAME  TestStartWriterAndReader
    session_test.go:244: Context still active before Stop()
==================
WARNING: DATA RACE
Write at 0x00c00014c4e0 by goroutine 16497:
  runtime.closechan()
      /opt/hostedtoolcache/go/1.24.7/x64/src/runtime/chan.go:414 +0x0
  github.com/leptonai/gpud/pkg/session.(*Session).Stop()
      /home/runner/work/gpud/gpud/pkg/session/session.go:659 +0x1a4
  github.com/leptonai/gpud/pkg/session.TestStartWriterAndReader()
      /home/runner/work/gpud/gpud/pkg/session/session_test.go:247 +0xf11
  testing.tRunner()
      /opt/hostedtoolcache/go/1.24.7/x64/src/testing/testing.go:1792 +0x225
  testing.(*T).Run.gowrap1()
      /opt/hostedtoolcache/go/1.24.7/x64/src/testing/testing.go:1851 +0x44

Previous read at 0x00c00014c4e0 by goroutine 16506:
  runtime.chansend()
      /opt/hostedtoolcache/go/1.24.7/x64/src/runtime/chan.go:176 +0x0
  github.com/leptonai/gpud/pkg/session.(*Session).tryWriteToReader()
      /home/runner/work/gpud/gpud/pkg/session/session.go:608 +0x6a4
  github.com/leptonai/gpud/pkg/session.(*Session).processReaderResponse()
      /home/runner/work/gpud/gpud/pkg/session/session.go:587 +0x37b
  github.com/leptonai/gpud/pkg/session.(*Session).startReader()
      /home/runner/work/gpud/gpud/pkg/session/session.go:539 +0xac4
  github.com/leptonai/gpud/pkg/session.(*Session).startReader-fm()
      <autogenerated>:1 +0x64
  github.com/leptonai/gpud/pkg/session.(*Session).keepAlive.gowrap1()
      /home/runner/work/gpud/gpud/pkg/session/session.go:367 +0x6e

Goroutine 16497 (running) created at:
  testing.(*T).Run()
      /opt/hostedtoolcache/go/1.24.7/x64/src/testing/testing.go:1851 +0x8f2
  testing.runTests.func1()
      /opt/hostedtoolcache/go/1.24.7/x64/src/testing/testing.go:2279 +0x85
  testing.tRunner()
      /opt/hostedtoolcache/go/1.24.7/x64/src/testing/testing.go:1792 +0x225
  testing.runTests()
      /opt/hostedtoolcache/go/1.24.7/x64/src/testing/testing.go:2277 +0x96c
  testing.(*M).Run()
      /opt/hostedtoolcache/go/1.24.7/x64/src/testing/testing.go:2142 +0xeea
  main.main()
      _testmain.go:155 +0x164

Goroutine 16506 (finished) created at:
  github.com/leptonai/gpud/pkg/session.(*Session).keepAlive()
      /home/runner/work/gpud/gpud/pkg/session/session.go:367 +0x80a
  github.com/leptonai/gpud/pkg/session.TestStartWriterAndReader.gowrap2()
      /home/runner/work/gpud/gpud/pkg/session/session_test.go:197 +0x33
==================
    testing.go:1490: race detected during execution of test
--- FAIL: TestStartWriterAndReader (0.81s)

Signed-off-by: Gyuho Lee gyuhol@nvidia.com

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 67.70%. Comparing base (fc398aa) to head (c183187).
⚠️ Report is 5 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1077      +/-   ##
==========================================
+ Coverage   67.65%   67.70%   +0.04%     
==========================================
  Files         313      313              
  Lines       26081    26081              
==========================================
+ Hits        17644    17657      +13     
+ Misses       7558     7547      -11     
+ Partials      879      877       -2     

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[gyuho]

Closing in favor of #1082