* [ruby-core:91703] [Ruby trunk Bug#15644] ThreadsWait problems with Thread#report_on_exception
[not found] <redmine.issue-15644.20190306132045@ruby-lang.org>
@ 2019-03-06 13:20 ` kimmo.lehto
2019-10-17 18:49 ` [ruby-core:95400] [Ruby master " merch-redmine
1 sibling, 0 replies; 2+ messages in thread
From: kimmo.lehto @ 2019-03-06 13:20 UTC (permalink / raw)
To: ruby-core
Issue #15644 has been reported by kke (Kimmo Lehto).
----------------------------------------
Bug #15644: ThreadsWait problems with Thread#report_on_exception
https://bugs.ruby-lang.org/issues/15644
* Author: kke (Kimmo Lehto)
* Status: Open
* Priority: Normal
* Assignee:
* Target version:
* ruby -v: ruby 2.6.1p33 (2019-01-30 revision 66950) [x86_64-darwin18]
* Backport: 2.4: UNKNOWN, 2.5: UNKNOWN, 2.6: UNKNOWN
----------------------------------------
ThreadsWait spawns a new thread for waiting on a thread:
```
# thwait.rb:87
def join_nowait(*threads)
threads.flatten!
@threads.concat threads
for th in threads
Thread.start(th) do |t|
begin
t.join
ensure
@wait_queue.push t
end
end
end
end
```
As `thread.join` raises the exception from the thread, it will trigger a thread exception report.
If the thread was using `report_on_exception = false`, the wait thread will report the exception anyway.
If the thread was using `report_on_exception = true`, both threads will report the exception.
I think this could be fixed by always setting `report_on_exception = false` for the wait thread.
# Example 1
```
require 'thwait'
thread = Thread.new do
Thread.current.report_on_exception = false
raise "Foo"
end
ThreadsWait.all_waits(thread) do |terminated_thread|
puts "Thread #{terminated_thread} terminated"
end
```
## Expected result
No exception reports
## Actual result
The wait thread will report the exception
# Example 2
```
require 'thwait'
thread = Thread.new do
raise "Foo"
end
ThreadsWait.all_waits(thread) do |terminated_thread|
puts "Thread #{terminated_thread} terminated"
end
```
## Expected result
One exception report
## Actual result
Two exception reports
--
https://bugs.ruby-lang.org/
^ permalink raw reply [flat|nested] 2+ messages in thread
* [ruby-core:95400] [Ruby master Bug#15644] ThreadsWait problems with Thread#report_on_exception
[not found] <redmine.issue-15644.20190306132045@ruby-lang.org>
2019-03-06 13:20 ` [ruby-core:91703] [Ruby trunk Bug#15644] ThreadsWait problems with Thread#report_on_exception kimmo.lehto
@ 2019-10-17 18:49 ` merch-redmine
1 sibling, 0 replies; 2+ messages in thread
From: merch-redmine @ 2019-10-17 18:49 UTC (permalink / raw)
To: ruby-core
Issue #15644 has been updated by jeremyevans0 (Jeremy Evans).
Assignee set to keiju (Keiju Ishitsuka)
Status changed from Open to Assigned
I agree this is a bug that should be fixed. I have submitted a pull request to fix it: https://github.com/ruby/thwait/pull/1
----------------------------------------
Bug #15644: ThreadsWait problems with Thread#report_on_exception
https://bugs.ruby-lang.org/issues/15644#change-82123
* Author: kke (Kimmo Lehto)
* Status: Assigned
* Priority: Normal
* Assignee: keiju (Keiju Ishitsuka)
* Target version:
* ruby -v: ruby 2.6.1p33 (2019-01-30 revision 66950) [x86_64-darwin18]
* Backport: 2.4: UNKNOWN, 2.5: UNKNOWN, 2.6: UNKNOWN
----------------------------------------
Using ThreadsWait with Thread.report_on_exception is confusing.
ThreadsWait spawns a new thread for waiting on a thread:
```
# thwait.rb:87
def join_nowait(*threads)
threads.flatten!
@threads.concat threads
for th in threads
Thread.start(th) do |t|
begin
t.join
ensure
@wait_queue.push t
end
end
end
end
```
The `t.join` in `ThreadsWait` will re-raise the exceptions that happen in the thread being waited on.
If the thread being waited on was using `report_on_exception = false`, the wait thread will report the exception and the `report_on_exception = false` effectively did nothing, as you still got an exception report.
If the thread was using `report_on_exception = true`, both threads will report the exception, so you get it twice.
I think this could be fixed by always setting `report_on_exception = false` for the wait thread.
# Example 1
```
require 'thwait'
thread = Thread.new do
Thread.current.report_on_exception = false
sleep 1
raise "Foo"
end
ThreadsWait.all_waits(thread) do |terminated_thread|
puts "Thread #{terminated_thread} terminated"
end
```
## Expected result
No exception reports
## Actual result
The wait thread will report the exception:
```
#<Thread:0x00007fa57d092d68@/Users/user/.rbenv/versions/2.6.1/lib/ruby/2.6.0/thwait.rb:91 run> terminated with exception (report_on_exception is true):
```
# Example 2
```
require 'thwait'
thread = Thread.new do
sleep 1
raise "Foo"
end
ThreadsWait.all_waits(thread) do |terminated_thread|
puts "Thread #{terminated_thread} terminated"
end
```
## Expected result
One exception report
## Actual result
Two exception reports:
```
#<Thread:0x00007f9f83053320@test.rb:3 run> terminated with exception (report_on_exception is true):
#<Thread:0x00007f9f830530a0@/Users/user/.rbenv/versions/2.6.1/lib/ruby/2.6.0/thwait.rb:91 run> terminated with exception (report_on_exception is true):
Traceback (most recent call last):
```
--
https://bugs.ruby-lang.org/
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[not found] <redmine.issue-15644.20190306132045@ruby-lang.org>
2019-03-06 13:20 ` [ruby-core:91703] [Ruby trunk Bug#15644] ThreadsWait problems with Thread#report_on_exception kimmo.lehto
2019-10-17 18:49 ` [ruby-core:95400] [Ruby master " merch-redmine
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