test/file: try to fix freezing of test_22566

[iblislin]

or any suggestion to test open_cloexec in src/support/ios.c ?

[vtjnash]

What does this do? A simple blocking read/write of a byte would be preferable to a timed sleep.

[iblislin]

@vtjnash recent CI build froze quite frequently after my PR #22566 merged.
I can reproduce the freezing on local via runing gmake test 2~5 times.
I attached my GDB to check the bt of workers, one of the workers stucks at the reader's open (r = open(fn, "r")).
So I guess that there is race condiction between the writer's open and reader's, but still no idea about the root cause.

[iblislin]

A simple blocking read/write of a byte would be preferable to a timed sleep.

I will try it tmr. :)

[iblislin]

+++ b/test/file.jl
@@ -1141,11 +1141,12 @@ if !Sys.iswindows()
         fn = tempname()
         run(`mkfifo $fn`)

-        script = "x = open(\"$fn\", \"w\"); sleep(0.1); close(x); quit()"
+        script = "x = open(\"$fn\", \"w\"); write(x, 0x42); flush(x); close(x); quit()"
         cmd = `$(Base.julia_cmd()) --startup-file=no -e $script`
         open(pipeline(cmd, stderr=STDERR))

         r = open(fn, "r")
+        @test read(r, Int64) == 66
         close(r)

         rm(fn)

got this

file: Error During Test
  Test threw an exception of type EOFError
  Expression: read(r, Int64) == 66
  EOFError: read end of file
  Stacktrace:
   [1] read at ./iostream.jl:202 [inlined]
   [2] test_22566() at /usr/home/iblis/git/julia/test/file.jl:1149
   [3] macro expansion at /usr/home/iblis/git/julia/test/file.jl:1157 [inlined]
   [4] anonymous at ./<missing>:?
   [5] include_relative(::Module, ::String) at ./loading.jl:464
   [6] include at ./sysimg.jl:14 [inlined]
   [7] include(::String) at /usr/home/iblis/git/julia/test/testdefs.jl:11
   [8] macro expansion at /usr/home/iblis/git/julia/test/testdefs.jl:18 [inlined]
   [9] macro expansion at ./test.jl:943 [inlined]
   [10] macro expansion at ./util.jl:379 [inlined]
   [11] macro expansion at /usr/home/iblis/git/julia/test/testdefs.jl:17 [inlined]
   [12] anonymous at ./<missing>:?

or I'm okay with getting rid of this test case..

[vtjnash]

write(x, 0x42);

You're only writing a byte, but attempting to read an Int64

[vtjnash]

while we're changing this test, can you replace \"$fn\" with $(repr(fn)) for me too? (that'll make it robust against other random meta-characters happening to to get inject into temp path)

[iblislin]

🆗