[jira] [Updated] (SPARK-2638) Improve concurrency of fetching Map outputs
[
https://issues.apache.org/jira/browse/SPARK-2638?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Patrick Wendell updated SPARK-2638:
---
Fix Version/s: (was: 1.2.0)
1.3.0
Improve concurrency of fetching Map outputs
---
Key: SPARK-2638
URL: https://issues.apache.org/jira/browse/SPARK-2638
Project: Spark
Issue Type: Improvement
Components: Spark Core
Affects Versions: 1.0.0
Environment: All
Reporter: Stephen Boesch
Assignee: Josh Rosen
Priority: Minor
Labels: MapOutput, concurrency
Fix For: 1.3.0
Original Estimate: 0h
Remaining Estimate: 0h
This issue was noticed while perusing the MapOutputTracker source code.
Notice that the synchronization is on the containing fetching collection -
which makes ALL fetches wait if any fetch were occurring.
The fix is to synchronize instead on the shuffleId (interned as a string to
ensure JVM wide visibility).
def getServerStatuses(shuffleId: Int, reduceId: Int):
Array[(BlockManagerId, Long)] = {
val statuses = mapStatuses.get(shuffleId).orNull
if (statuses == null) {
logInfo(Don't have map outputs for shuffle + shuffleId + , fetching
them)
var fetchedStatuses: Array[MapStatus] = null
fetching.synchronized { // This is existing code
// shuffleId.toString.intern.synchronized { // New Code
if (fetching.contains(shuffleId)) {
// Someone else is fetching it; wait for them to be done
while (fetching.contains(shuffleId)) {
try {
fetching.wait()
} catch {
case e: InterruptedException =
}
}
This is only a small code change, but the testcases to prove (a) proper
functionality and (b) proper performance improvement are not so trivial.
For (b) it is not worthwhile to add a testcase to the codebase. Instead I
have added a git project that demonstrates the concurrency/performance
improvement using the fine-grained approach . The github project is at
https://github.com/javadba/scalatesting.git . Simply run sbt test. Note:
it is unclear how/where to include this ancillary testing/verification
information that will not be included in the git PR: i am open for any
suggestions - even as far as simply removing references to it.
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[jira] [Updated] (SPARK-2638) Improve concurrency of fetching Map outputs
[
https://issues.apache.org/jira/browse/SPARK-2638?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Patrick Wendell updated SPARK-2638:
---
Fix Version/s: (was: 1.3.0)
Improve concurrency of fetching Map outputs
---
Key: SPARK-2638
URL: https://issues.apache.org/jira/browse/SPARK-2638
Project: Spark
Issue Type: Improvement
Components: Spark Core
Affects Versions: 1.0.0
Environment: All
Reporter: Stephen Boesch
Assignee: Josh Rosen
Priority: Minor
Labels: MapOutput, concurrency
Original Estimate: 0h
Remaining Estimate: 0h
This issue was noticed while perusing the MapOutputTracker source code.
Notice that the synchronization is on the containing fetching collection -
which makes ALL fetches wait if any fetch were occurring.
The fix is to synchronize instead on the shuffleId (interned as a string to
ensure JVM wide visibility).
def getServerStatuses(shuffleId: Int, reduceId: Int):
Array[(BlockManagerId, Long)] = {
val statuses = mapStatuses.get(shuffleId).orNull
if (statuses == null) {
logInfo(Don't have map outputs for shuffle + shuffleId + , fetching
them)
var fetchedStatuses: Array[MapStatus] = null
fetching.synchronized { // This is existing code
// shuffleId.toString.intern.synchronized { // New Code
if (fetching.contains(shuffleId)) {
// Someone else is fetching it; wait for them to be done
while (fetching.contains(shuffleId)) {
try {
fetching.wait()
} catch {
case e: InterruptedException =
}
}
This is only a small code change, but the testcases to prove (a) proper
functionality and (b) proper performance improvement are not so trivial.
For (b) it is not worthwhile to add a testcase to the codebase. Instead I
have added a git project that demonstrates the concurrency/performance
improvement using the fine-grained approach . The github project is at
https://github.com/javadba/scalatesting.git . Simply run sbt test. Note:
it is unclear how/where to include this ancillary testing/verification
information that will not be included in the git PR: i am open for any
suggestions - even as far as simply removing references to it.
--
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[jira] [Updated] (SPARK-2638) Improve concurrency of fetching Map outputs
[
https://issues.apache.org/jira/browse/SPARK-2638?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Patrick Wendell updated SPARK-2638:
---
Fix Version/s: (was: 1.1.0)
1.2.0
Improve concurrency of fetching Map outputs
---
Key: SPARK-2638
URL: https://issues.apache.org/jira/browse/SPARK-2638
Project: Spark
Issue Type: Improvement
Components: Spark Core
Affects Versions: 1.0.0
Environment: All
Reporter: Stephen Boesch
Assignee: Josh Rosen
Priority: Minor
Labels: MapOutput, concurrency
Fix For: 1.2.0
Original Estimate: 0h
Remaining Estimate: 0h
This issue was noticed while perusing the MapOutputTracker source code.
Notice that the synchronization is on the containing fetching collection -
which makes ALL fetches wait if any fetch were occurring.
The fix is to synchronize instead on the shuffleId (interned as a string to
ensure JVM wide visibility).
def getServerStatuses(shuffleId: Int, reduceId: Int):
Array[(BlockManagerId, Long)] = {
val statuses = mapStatuses.get(shuffleId).orNull
if (statuses == null) {
logInfo(Don't have map outputs for shuffle + shuffleId + , fetching
them)
var fetchedStatuses: Array[MapStatus] = null
fetching.synchronized { // This is existing code
// shuffleId.toString.intern.synchronized { // New Code
if (fetching.contains(shuffleId)) {
// Someone else is fetching it; wait for them to be done
while (fetching.contains(shuffleId)) {
try {
fetching.wait()
} catch {
case e: InterruptedException =
}
}
This is only a small code change, but the testcases to prove (a) proper
functionality and (b) proper performance improvement are not so trivial.
For (b) it is not worthwhile to add a testcase to the codebase. Instead I
have added a git project that demonstrates the concurrency/performance
improvement using the fine-grained approach . The github project is at
https://github.com/javadba/scalatesting.git . Simply run sbt test. Note:
it is unclear how/where to include this ancillary testing/verification
information that will not be included in the git PR: i am open for any
suggestions - even as far as simply removing references to it.
--
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