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Posted to common-issues@hadoop.apache.org by "jojochuang (via GitHub)" <gi...@apache.org> on 2023/05/23 23:45:01 UTC
[GitHub] [hadoop] jojochuang opened a new pull request, #5687: HDFS-17024. Potential data race introduced by HDFS-15865.
jojochuang opened a new pull request, #5687:
URL: https://github.com/apache/hadoop/pull/5687
### Description of PR
https://issues.apache.org/jira/browse/HDFS-17024
### How was this patch tested?
Existing unit tests
This is an improvement. I don't think it's possible to reproduce the data race.
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Re: [PR] HDFS-17024. Potential data race introduced by HDFS-15865. [hadoop]
Posted by "jojochuang (via GitHub)" <gi...@apache.org>.
jojochuang commented on code in PR #5687:
URL: https://github.com/apache/hadoop/pull/5687#discussion_r1351520185
##########
hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DataStreamer.java:
##########
@@ -916,7 +917,7 @@ void waitForAckedSeqno(long seqno) throws IOException {
try (TraceScope ignored = dfsClient.getTracer().
newScope("waitForAckedSeqno")) {
LOG.debug("{} waiting for ack for: {}", this, seqno);
- int dnodes = nodes != null ? nodes.length : 3;
+ int dnodes = nodes.length > 0 ? nodes.length : 3;
Review Comment:
volatile does not guarantee that. You'd need something similar to AtomicInteger.compareAndSet()
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[GitHub] [hadoop] hadoop-yetus commented on pull request #5687: HDFS-17024. Potential data race introduced by HDFS-15865.
Posted by "hadoop-yetus (via GitHub)" <gi...@apache.org>.
hadoop-yetus commented on PR #5687:
URL: https://github.com/apache/hadoop/pull/5687#issuecomment-1560329552
:broken_heart: **-1 overall**
| Vote | Subsystem | Runtime | Logfile | Comment |
|:----:|----------:|--------:|:--------:|:-------:|
| +0 :ok: | reexec | 0m 36s | | Docker mode activated. |
|||| _ Prechecks _ |
| +1 :green_heart: | dupname | 0m 0s | | No case conflicting files found. |
| +0 :ok: | codespell | 0m 0s | | codespell was not available. |
| +0 :ok: | detsecrets | 0m 0s | | detect-secrets was not available. |
| +1 :green_heart: | @author | 0m 0s | | The patch does not contain any @author tags. |
| -1 :x: | test4tests | 0m 0s | | The patch doesn't appear to include any new or modified tests. Please justify why no new tests are needed for this patch. Also please list what manual steps were performed to verify this patch. |
|||| _ trunk Compile Tests _ |
| +1 :green_heart: | mvninstall | 33m 15s | | trunk passed |
| +1 :green_heart: | compile | 1m 0s | | trunk passed with JDK Ubuntu-11.0.19+7-post-Ubuntu-0ubuntu120.04.1 |
| +1 :green_heart: | compile | 0m 52s | | trunk passed with JDK Private Build-1.8.0_362-8u372-ga~us1-0ubuntu1~20.04-b09 |
| +1 :green_heart: | checkstyle | 0m 37s | | trunk passed |
| +1 :green_heart: | mvnsite | 0m 56s | | trunk passed |
| +1 :green_heart: | javadoc | 0m 51s | | trunk passed with JDK Ubuntu-11.0.19+7-post-Ubuntu-0ubuntu120.04.1 |
| +1 :green_heart: | javadoc | 0m 39s | | trunk passed with JDK Private Build-1.8.0_362-8u372-ga~us1-0ubuntu1~20.04-b09 |
| +1 :green_heart: | spotbugs | 2m 40s | | trunk passed |
| +1 :green_heart: | shadedclient | 22m 1s | | branch has no errors when building and testing our client artifacts. |
|||| _ Patch Compile Tests _ |
| +1 :green_heart: | mvninstall | 0m 44s | | the patch passed |
| +1 :green_heart: | compile | 0m 49s | | the patch passed with JDK Ubuntu-11.0.19+7-post-Ubuntu-0ubuntu120.04.1 |
| +1 :green_heart: | javac | 0m 49s | | the patch passed |
| +1 :green_heart: | compile | 0m 42s | | the patch passed with JDK Private Build-1.8.0_362-8u372-ga~us1-0ubuntu1~20.04-b09 |
| +1 :green_heart: | javac | 0m 42s | | the patch passed |
| +1 :green_heart: | blanks | 0m 0s | | The patch has no blanks issues. |
| +1 :green_heart: | checkstyle | 0m 19s | | the patch passed |
| +1 :green_heart: | mvnsite | 0m 47s | | the patch passed |
| +1 :green_heart: | javadoc | 0m 35s | | the patch passed with JDK Ubuntu-11.0.19+7-post-Ubuntu-0ubuntu120.04.1 |
| +1 :green_heart: | javadoc | 0m 32s | | the patch passed with JDK Private Build-1.8.0_362-8u372-ga~us1-0ubuntu1~20.04-b09 |
| +1 :green_heart: | spotbugs | 2m 31s | | the patch passed |
| +1 :green_heart: | shadedclient | 21m 38s | | patch has no errors when building and testing our client artifacts. |
|||| _ Other Tests _ |
| +1 :green_heart: | unit | 2m 22s | | hadoop-hdfs-client in the patch passed. |
| +1 :green_heart: | asflicense | 0m 37s | | The patch does not generate ASF License warnings. |
| | | 95m 24s | | |
| Subsystem | Report/Notes |
|----------:|:-------------|
| Docker | ClientAPI=1.43 ServerAPI=1.43 base: https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-5687/1/artifact/out/Dockerfile |
| GITHUB PR | https://github.com/apache/hadoop/pull/5687 |
| Optional Tests | dupname asflicense compile javac javadoc mvninstall mvnsite unit shadedclient spotbugs checkstyle codespell detsecrets |
| uname | Linux cc3706a61c50 4.15.0-206-generic #217-Ubuntu SMP Fri Feb 3 19:10:13 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux |
| Build tool | maven |
| Personality | dev-support/bin/hadoop.sh |
| git revision | trunk / be611ada16fb9befbdd3cde39bdd45506c96d640 |
| Default Java | Private Build-1.8.0_362-8u372-ga~us1-0ubuntu1~20.04-b09 |
| Multi-JDK versions | /usr/lib/jvm/java-11-openjdk-amd64:Ubuntu-11.0.19+7-post-Ubuntu-0ubuntu120.04.1 /usr/lib/jvm/java-8-openjdk-amd64:Private Build-1.8.0_362-8u372-ga~us1-0ubuntu1~20.04-b09 |
| Test Results | https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-5687/1/testReport/ |
| Max. process+thread count | 733 (vs. ulimit of 5500) |
| modules | C: hadoop-hdfs-project/hadoop-hdfs-client U: hadoop-hdfs-project/hadoop-hdfs-client |
| Console output | https://ci-hadoop.apache.org/job/hadoop-multibranch/job/PR-5687/1/console |
| versions | git=2.25.1 maven=3.6.3 spotbugs=4.2.2 |
| Powered by | Apache Yetus 0.14.0 https://yetus.apache.org |
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Re: [PR] HDFS-17024. Potential data race introduced by HDFS-15865. [hadoop]
Posted by "LiuGuH (via GitHub)" <gi...@apache.org>.
LiuGuH commented on code in PR #5687:
URL: https://github.com/apache/hadoop/pull/5687#discussion_r1349654905
##########
hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DataStreamer.java:
##########
@@ -916,7 +917,7 @@ void waitForAckedSeqno(long seqno) throws IOException {
try (TraceScope ignored = dfsClient.getTracer().
newScope("waitForAckedSeqno")) {
LOG.debug("{} waiting for ack for: {}", this, seqno);
- int dnodes = nodes != null ? nodes.length : 3;
+ int dnodes = nodes.length > 0 ? nodes.length : 3;
Review Comment:
The nodes are not thread-safe. So int currentNodes = nodes.length will maybe NPE.
Use thread-safe data structures or a lock?
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[GitHub] [hadoop] sodonnel commented on a diff in pull request #5687: HDFS-17024. Potential data race introduced by HDFS-15865.
Posted by "sodonnel (via GitHub)" <gi...@apache.org>.
sodonnel commented on code in PR #5687:
URL: https://github.com/apache/hadoop/pull/5687#discussion_r1203703794
##########
hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DataStreamer.java:
##########
@@ -916,7 +917,7 @@ void waitForAckedSeqno(long seqno) throws IOException {
try (TraceScope ignored = dfsClient.getTracer().
newScope("waitForAckedSeqno")) {
LOG.debug("{} waiting for ack for: {}", this, seqno);
- int dnodes = nodes != null ? nodes.length : 3;
+ int dnodes = nodes.length > 0 ? nodes.length : 3;
Review Comment:
I think there is still a risk of a race here. In the original problem after nodes.length evaulated to say 3, then nodes was set to null. Then the "IF" statement tried to call null.length, leading to the error.
In this changed code, you could evaluate nodes.length to get 3, and then nodes is swapped to be the new `EMPTY_DATANODES`, then in the IF statement its length will be zero, setting dnodes to zero rather than 3, which will probably trip up the `getDatanodeWriteTimeout` method it is passed too.
To make it safe, you probably have to:
```
int currentNodes = nodes.length;
int dnodes = currentNodes > 0 ? currentNoides : 3;
```
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Re: [PR] HDFS-17024. Potential data race introduced by HDFS-15865. [hadoop]
Posted by "LiuGuH (via GitHub)" <gi...@apache.org>.
LiuGuH commented on code in PR #5687:
URL: https://github.com/apache/hadoop/pull/5687#discussion_r1349654905
##########
hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DataStreamer.java:
##########
@@ -916,7 +917,7 @@ void waitForAckedSeqno(long seqno) throws IOException {
try (TraceScope ignored = dfsClient.getTracer().
newScope("waitForAckedSeqno")) {
LOG.debug("{} waiting for ack for: {}", this, seqno);
- int dnodes = nodes != null ? nodes.length : 3;
+ int dnodes = nodes.length > 0 ? nodes.length : 3;
Review Comment:
The nodes are not thread-safe. So int currentNodes = nodes.length will maybe NPE.
Use thread-safe data structures or a lock?
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Re: [PR] HDFS-17024. Potential data race introduced by HDFS-15865. [hadoop]
Posted by "LiuGuH (via GitHub)" <gi...@apache.org>.
LiuGuH commented on code in PR #5687:
URL: https://github.com/apache/hadoop/pull/5687#discussion_r1351293511
##########
hadoop-hdfs-project/hadoop-hdfs-client/src/main/java/org/apache/hadoop/hdfs/DataStreamer.java:
##########
@@ -916,7 +917,7 @@ void waitForAckedSeqno(long seqno) throws IOException {
try (TraceScope ignored = dfsClient.getTracer().
newScope("waitForAckedSeqno")) {
LOG.debug("{} waiting for ack for: {}", this, seqno);
- int dnodes = nodes != null ? nodes.length : 3;
+ int dnodes = nodes.length > 0 ? nodes.length : 3;
Review Comment:
The nodes are protected by volatile and it will be assigned by EMPTY_DATANODES. So I think odes.length will not be NPE.
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