Run thread-safety checks when Julia is using threads (JuliaTime#387)

* Run thread-safety checks when Julia is using threads

* Use 8-threads specifically

* Reset cache for thread-safety checks

.github/workflows/CI.yml

@@ -66,6 +66,8 @@ jobs:
  TZDATA_VERSION: 2016j # Matches tzdata version used in tests
  - uses: julia-actions/julia-buildpkg@latest
  - uses: julia-actions/julia-runtest@latest
+ env:
+ JULIA_NUM_THREADS: "8" # Can probably use "auto" here instead
  - uses: julia-actions/julia-processcoverage@v1
  - uses: codecov/codecov-action@v2
  with:

test/runtests.jl

@@ -68,7 +68,15 @@ include("helpers.jl")
  include("rounding.jl")
  include("parse.jl")
  include("plotting.jl")
- include("thread-safety.jl")
+
+ is_apple_silicon = first(Sys.cpu_info()).model == "Apple M1"
+ if is_apple_silicon && Threads.nthreads() == 8
+ @info "Thread safety tests can hang on Apple Silicon when using 8-threads. Use 7-threads instead"
+ elseif Threads.nthreads() == 1
+ @info "Skipping thread safety check as Julia was started with a single thread"
+ else
+ include("thread-safety.jl")
+ end
 
  # Note: Run the build tests last to ensure that re-compiling the time zones files
  # doesn't interfere with other tests.

test/thread-safety.jl

@@ -1,72 +1,53 @@
-# Test that TimeZones.jl can be safely used in a multithreaded environment.
-# Note that the number of threads being used cannot be changed dynamically, so
-# this test file spawns a new julia process running with multiple threads.
-
-using Test
+@testset "Thread safety" begin
+ # Reset the cache before running the thread-safety tests to increase the chance of an
+ # issue occurring when multiple threads load data at the same time.
+ TimeZones._reset_tz_cache()
+
+ @testset "Multithreaded TimeZone brute force test" begin
+ function create_zdt(year, month, day, tz_name)
+ ZonedDateTime(DateTime(year, month, day), TimeZone(tz_name))
+ end
+ function cycle_zdts()
+ return [
+ try
+ create_zdt(year, month, day, tz_name)
+ catch e
+ # Ignore ZonedDateTimes that aren't valid
+ e isa Union{ArgumentError,AmbiguousTimeError,NonExistentTimeError} || rethrow()
+ nothing
+ end
+ for year in 2000:2020
+ for month in 1:5
+ for day in 10:15
+ for tz_name in timezone_names()
+ ]
+ end
 
-const program = """
-using TimeZones
-using Test
+ outputs = Channel(Inf)
+ @sync begin
+ for _ in 1:15
+ Threads.@spawn begin
+ put!(outputs, cycle_zdts())
+ end
+ end
+ end
+ close(outputs)
 
-@assert Threads.nthreads() > 1 "This system does not support multiple threads, so the thread-safety tests cannot be run."
+ tzs = collect(outputs)
 
-@testset "Multithreaded TimeZone brute force test" begin
- function create_zdt(year, month, day, tz_name)
- ZonedDateTime(DateTime(year, month, day), TimeZone(tz_name))
- end
- function cycle_zdts()
- return [
- try
- create_zdt(year, month, day, tz_name)
- catch e
- # Ignore ZonedDateTimes that aren't valid
- e isa Union{ArgumentError,AmbiguousTimeError,NonExistentTimeError} || rethrow()
- nothing
- end
- for year in 2000:2020
- for month in 1:5
- for day in 10:15
- for tz_name in timezone_names()
- ]
+ # Test that every Task produced the same result
+ allsame(x) = all(y -> y == first(x), x)
+ @test allsame(tzs)
  end
 
- outputs = Channel(Inf)
- @sync begin
- for _ in 1:15
+ @testset "Interleaved compile() and TimeZone construction" begin
+ @sync for i in 1:20
+ if (i % 5 == 0)
+ TimeZones.TZData.compile()
+ end
  Threads.@spawn begin
- put!(outputs, cycle_zdts())
+ TimeZone("US/Eastern", TimeZones.Class(:LEGACY))
  end
  end
  end
- close(outputs)
-
- tzs = collect(outputs)
-
- # Test that every Task produced the same result
- allsame(x) = all(y -> y == first(x), x)
- @test allsame(tzs)
-end
-
-#----------------------------------------------------
-
-@testset "Interleaved compile() and TimeZone construction" begin
- @sync for i in 1:20
- if (i % 5 == 0)
- TimeZones.TZData.compile()
- end
- Threads.@spawn begin
- TimeZone("US/Eastern", TimeZones.Class(:LEGACY))
- end
- end
-end
-"""
-
-@info "Running Thread Safety tests"
-@testset "Multithreaded TimeZone construction" begin
- # Workaround for Apple Silicon hanging when using 8 threads
- nthreads = first(Sys.cpu_info()).model == "Apple M1" ? 7 : 8
-
- withenv("JULIA_NUM_THREADS" => nthreads) do
- run(`$(Base.julia_cmd()) --proj -E $(program)`)
- end
 end