Checkpoint synchronization: Difference between revisions
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Scala contribution added. |
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{}</pre>
=={{header|
<lang Scala>import java.util.{Random, Scanner}
object CheckpointSync extends App {
val in = new Scanner(System.in)
/*
* Informs that workers started working on the task and
* starts running threads. Prior to proceeding with next
* task syncs using static Worker.checkpoint() method.
*/
private def runTasks(nTasks: Int): Unit = {
for (i <- 0 until nTasks) {
println("Starting task number " + (i + 1) + ".")
runThreads()
Worker.checkpoint()
}
}
/*
* Creates a thread for each worker and runs it.
*/
private def runThreads(): Unit =
for (i <- 0 until Worker.nWorkers) new Thread(new Worker(i + 1)).start()
class Worker(/* inner class instance variables */ var threadID: Int)
extends Runnable {
override def run(): Unit = {
work()
}
/*
* Notifies that thread started running for 100 to 1000 msec.
* Once finished increments static counter 'nFinished'
* that counts number of workers finished their work.
*/
private def work(): Unit = {
try {
val workTime = Worker.rgen.nextInt(900) + 100
println("Worker " + threadID + " will work for " + workTime + " msec.")
Thread.sleep(workTime) //work for 'workTime'
Worker.nFinished += 1 //increases work finished counter
println("Worker " + threadID + " is ready")
} catch {
case e: InterruptedException =>
System.err.println("Error: thread execution interrupted")
e.printStackTrace()
}
}
}
/*
* Worker inner static class.
*/
object Worker {
private val rgen = new Random
var nWorkers = 0
private var nFinished = 0
/*
* Used to synchronize Worker threads using 'nFinished' static integer.
* Waits (with step of 10 msec) until 'nFinished' equals to 'nWorkers'.
* Once they are equal resets 'nFinished' counter.
*/
def checkpoint(): Unit = {
while (nFinished != nWorkers)
try Thread.sleep(10)
catch {
case e: InterruptedException =>
System.err.println("Error: thread execution interrupted")
e.printStackTrace()
}
nFinished = 0
}
}
print("Enter number of workers to use: ")
Worker.nWorkers = in.nextInt
print("Enter number of tasks to complete:")
runTasks(in.nextInt)
}</lang>
=={{header|Tcl}}==
This implementation works by having a separate thread handle the synchronization (inter-thread message delivery already being serialized). The alternative, using a read-write mutex, is more complex and more likely to run into trouble with multi-core machines.
<lang tcl>package require Tcl 8.5
Line 2,667 ⟶ 2,752:
A is ready
B is ready
D is ready</pre>
=={{header|zkl}}==
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