Github user CodingCat commented on a diff in the pull request:
https://github.com/apache/spark/pull/228#discussion_r10948890
--- Diff: core/src/main/scala/org/apache/spark/Accumulators.scala ---
@@ -43,8 +44,10 @@ class Accumulable[R, T] (
param: AccumulableParam[R, T])
extends Serializable {
- val id = Accumulators.newId
- @transient private var value_ = initialValue // Current value on master
+ val id = Accumulators.nextAccumID.get()
+ Accumulators.nextAccumID.getAndIncrement
--- End diff --
In the original implementation, id is an integer and increased with
synchronized{} guard, just make it as an AtomicLong for convenience. Here the
two lines are get the value and increment
Ah, I think I know why you are confused here, the more straightforward way
seems to be
```
val id = Accumulator.nextAccumID.getAndIncrement
```
I tried that, but I found that the id field will be called for two times
during the initilaization(?) of a task, so for every time, the id is
increased...
I have to get the value when call id but increment in the constructor of
Accumulable
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