Comments (2)
Hey Brandon! thanks man, I'm glad this library is useful for you 🙂
That's right, that happens because Go reuses the same variable when iterating through an array or slice. In your example, the item
variable is reused in every iteration, so its memory address never changes, only its value is updated. That's why all the goroutines (which very likely end up running after the iteration is completed) see the same value at the moment of printing it.
There are several ways to prevent this, but here are 2 of the most common ones:
pool := pond.New(10, 0)
// Solution 1: creating a local copy of the iteration variable and using the copy inside the function
for _, item := range element {
itemCopy := item
pool.Submit(func() {
fmt.Printf("%v", itemCopy)
})
}
// Solution 2: creating an annonymous function that's immediately invoked with the iterator value
for _, item := range element {
// Here you'll need to replace interface{} by the actual type of item
pool.Submit(func(item interface{}) func() {
return func() {
fmt.Printf("%v", item)
}
}(item))
}
pool.StopAndWait()
The second solution doesn't look very nice tbh, but it should work 🙂
Here's an article that explains this situation with greater detail: https://github.com/golang/go/wiki/CommonMistakes#using-goroutines-on-loop-iterator-variables
Have a nice day! and please let me know if that worked for you.
from pond.
Wow, thank you so much -- that worked perfectly. Have a nice day as well!
from pond.
Related Issues (20)
- add support go 1.17.x HOT 11
- Iterating over a slice of strings (paths to files) and applying this to it HOT 2
- Why use atomic.AddInt32() and sync.Mutex at the same time HOT 2
- Access channel concurrently HOT 3
- Exceptions may occur when closing the pool HOT 7
- does pond support serial queue? HOT 3
- Question: What happens to the pool when a worker panic HOT 3
- goroutine running on other thread; stack unavailable HOT 2
- error handling HOT 4
- Deadlock on zero minimum workers HOT 3
- Unaligned 64-bit atomic operation error when built for linux HOT 2
- pond.New(30, 100, pond.MinWorkers(30)) creates 60 goroutines not 30 HOT 2
- Crash on arm 32-bits (RPi4)
- panic: send on closed channel, when lots of goroutine are running(may be for a long time) HOT 3
- IdleWorkers RunningWorkers HOT 3
- metric problem HOT 3
- run stop panic
- support task priority
- 1 pool for 3 different tasks with the same number of workers on each task HOT 1
- Will requesting to submit an asynchronous task cause blocking? HOT 1
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from pond.