[GitHub] [hadoop] jojochuang commented on a change in pull request #3148: HDFS-16090. Fine grained lock for datanodeNetworkCounts
jojochuang commented on a change in pull request #3148:
URL: https://github.com/apache/hadoop/pull/3148#discussion_r659593859
##
File path:
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataNode.java
##
@@ -2272,19 +2274,11 @@ public int getActiveTransferThreadCount() {
void incrDatanodeNetworkErrors(String host) {
metrics.incrDatanodeNetworkErrors();
-/*
- * Synchronizing on the whole cache is a big hammer, but since it's only
- * accumulating errors, it should be ok. If this is ever expanded to
include
- * non-error stats, then finer-grained concurrency should be applied.
- */
-synchronized (datanodeNetworkCounts) {
- try {
-final Map curCount = datanodeNetworkCounts.get(host);
-curCount.put("networkErrors", curCount.get("networkErrors") + 1L);
-datanodeNetworkCounts.put(host, curCount);
- } catch (ExecutionException e) {
-LOG.warn("failed to increment network error counts for host: {}",
host);
- }
+try {
+ datanodeNetworkCounts.get(host).compute(NETWORK_ERRORS,
+ (key, errors) -> errors == null ? null : errors + 1L);
Review comment:
i mean, shouldn't it be made 1 when errors is null (meaning the key
didn't exist before)?
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[GitHub] [hadoop] jojochuang commented on a change in pull request #3148: HDFS-16090. Fine grained lock for datanodeNetworkCounts
jojochuang commented on a change in pull request #3148:
URL: https://github.com/apache/hadoop/pull/3148#discussion_r659593248
##
File path:
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataNode.java
##
@@ -2272,19 +2274,11 @@ public int getActiveTransferThreadCount() {
void incrDatanodeNetworkErrors(String host) {
metrics.incrDatanodeNetworkErrors();
-/*
- * Synchronizing on the whole cache is a big hammer, but since it's only
- * accumulating errors, it should be ok. If this is ever expanded to
include
- * non-error stats, then finer-grained concurrency should be applied.
- */
-synchronized (datanodeNetworkCounts) {
- try {
-final Map curCount = datanodeNetworkCounts.get(host);
-curCount.put("networkErrors", curCount.get("networkErrors") + 1L);
-datanodeNetworkCounts.put(host, curCount);
- } catch (ExecutionException e) {
-LOG.warn("failed to increment network error counts for host: {}",
host);
- }
+try {
+ datanodeNetworkCounts.get(host).compute(NETWORK_ERRORS,
+ (key, errors) -> errors == null ? null : errors + 1L);
Review comment:
not familiar with ConcurrentHashMap.compute() but wouldn't this make
errors null always?
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