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Is this logging appropriate? #382
Description
I'm seeing some warnings in my tests about tasks that 'may have ended with unhandled exception.'
I can't tell if this is async being overly cautious, or if I'm actually doing something wrong. As far as I can tell, this code is correct:
Code:
def async_map(items:, concurrency_limit: Float::INFINITY, &block)
result = []
Async do
semaphore = Async::Semaphore.new(concurrency_limit)
tasks = items.map do |item|
semaphore.async do
yield(item)
end
end
result = tasks.map(&:wait)
end.wait
return result
endSpec:
require "rails_helper"
RSpec.describe AsyncUtils do
describe ".async_map" do
subject { described_class.async_map(items:, concurrency_limit:, &block) }
context "when the block raises an error" do
let(:block) { ->(_) { raise "test error" } }
let(:items) { [1, 2, 3] }
let(:concurrency_limit) { Float::INFINITY }
it "propagates the error" do
expect { subject }.to raise_error("test error")
end
end
end
endTest output:
when the block raises an error
0.0s warn: Async::Task [oid=0x7b34] [ec=0x7b48] [pid=150195] [2025-04-09 11:52:45 +0000]
| Task may have ended with unhandled exception.
| RuntimeError: test error
| → spec/services/async_utils_spec.rb:40 in `block (5 levels) in <top (required)>'
| app/services/async_utils.rb:20 in `block (3 levels) in async_map'
| /api-bundle/ruby/3.3.0/gems/async-2.23.1/lib/async/semaphore.rb:68 in `block in async'
| /api-bundle/ruby/3.3.0/gems/async-2.23.1/lib/async/task.rb:200 in `block in run'
| /api-bundle/ruby/3.3.0/gems/async-2.23.1/lib/async/task.rb:438 in `block in schedule'
0.0s warn: Async::Task [oid=0x7b5c] [ec=0x7b70] [pid=150195] [2025-04-09 11:52:45 +0000]
| Task may have ended with unhandled exception.
| RuntimeError: test error
| → spec/services/async_utils_spec.rb:40 in `block (5 levels) in <top (required)>'
| app/services/async_utils.rb:20 in `block (3 levels) in async_map'
| /api-bundle/ruby/3.3.0/gems/async-2.23.1/lib/async/semaphore.rb:68 in `block in async'
| /api-bundle/ruby/3.3.0/gems/async-2.23.1/lib/async/task.rb:200 in `block in run'
| /api-bundle/ruby/3.3.0/gems/async-2.23.1/lib/async/task.rb:438 in `block in schedule'
0.0s warn: Async::Task [oid=0x7b84] [ec=0x7b98] [pid=150195] [2025-04-09 11:52:45 +0000]
| Task may have ended with unhandled exception.
| RuntimeError: test error
| → spec/services/async_utils_spec.rb:40 in `block (5 levels) in <top (required)>'
| app/services/async_utils.rb:20 in `block (3 levels) in async_map'
| /api-bundle/ruby/3.3.0/gems/async-2.23.1/lib/async/semaphore.rb:68 in `block in async'
| /api-bundle/ruby/3.3.0/gems/async-2.23.1/lib/async/task.rb:200 in `block in run'
| /api-bundle/ruby/3.3.0/gems/async-2.23.1/lib/async/task.rb:438 in `block in schedule'
0.0s warn: Async::Task [oid=0x7bac] [ec=0x7bc0] [pid=150195] [2025-04-09 11:52:45 +0000]
| Task may have ended with unhandled exception.
| RuntimeError: test error
| → spec/services/async_utils_spec.rb:40 in `block (5 levels) in <top (required)>'
| app/services/async_utils.rb:20 in `block (3 levels) in async_map'
| /api-bundle/ruby/3.3.0/gems/async-2.23.1/lib/async/semaphore.rb:68 in `block in async'
| /api-bundle/ruby/3.3.0/gems/async-2.23.1/lib/async/task.rb:200 in `block in run'
| /api-bundle/ruby/3.3.0/gems/async-2.23.1/lib/async/task.rb:438 in `block in schedule'
So my question is: should I just disable these noisy logs, or do they necessarily point to actual problems in my code? Thanks.
Activity
ioquatix commentedon Apr 9, 2025
You should check out this PR: socketry/async-await#10, basically add
finished: falsewhich indicates that while we aren't waiting yet, we will eventually wait.finished: nil(the default) means unspecified and will log an exception because we don't know if it is going to be handled or not. Unfortunately Async cannot read the future.