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Posted to issues@flink.apache.org by GitBox <gi...@apache.org> on 2022/07/22 15:33:45 UTC
[GitHub] [flink] pnowojski commented on a diff in pull request #20245: [FLINK-28487][connectors] Introduce configurable RateLimitingStrategy…
pnowojski commented on code in PR #20245:
URL: https://github.com/apache/flink/pull/20245#discussion_r927747602
##########
flink-connectors/flink-connector-base/src/main/java/org/apache/flink/connector/base/sink/writer/strategy/AIMDScalingStrategy.java:
##########
@@ -0,0 +1,85 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.connector.base.sink.writer.strategy;
+
+import org.apache.flink.annotation.PublicEvolving;
+import org.apache.flink.util.Preconditions;
+
+/**
+ * AIMDScalingStrategy scales up linearly and scales down multiplicatively. See
+ * https://en.wikipedia.org/wiki/Additive_increase/multiplicative_decrease for more details
+ */
+@PublicEvolving
+public class AIMDScalingStrategy {
+ private final int increaseRate;
+ private final double decreaseFactor;
+ private final int rateThreshold;
+
+ public AIMDScalingStrategy(int increaseRate, double decreaseFactor, int rateThreshold) {
+ Preconditions.checkArgument(increaseRate > 0, "increaseRate must be positive integer.");
+ Preconditions.checkArgument(
+ decreaseFactor < 1.0 && decreaseFactor > 0.0,
+ "decreaseFactor must be strictly between 0.0 and 1.0.");
+ Preconditions.checkArgument(rateThreshold > 0, "rateThreshold must be a positive integer.");
+ Preconditions.checkArgument(
+ rateThreshold >= increaseRate, "rateThreshold must be larger than increaseRate.");
+ this.increaseRate = increaseRate;
+ this.decreaseFactor = decreaseFactor;
+ this.rateThreshold = rateThreshold;
+ }
+
+ public int scaleUp(int currentRate) {
+ return Math.min(currentRate + increaseRate, rateThreshold);
+ }
+
+ public int scaleDown(int currentRate) {
+ return Math.max(1, (int) Math.round(currentRate * decreaseFactor));
+ }
+
+ @PublicEvolving
+ public static AIMDScalingStrategyBuilder builder() {
+ return new AIMDScalingStrategyBuilder();
+ }
+
+ /** Builder for {@link AIMDScalingStrategy}. */
+ public static class AIMDScalingStrategyBuilder {
+
+ private int increaseRate = 10;
+ private double decreaseFactor = 0.5;
+ private int rateThreshold;
Review Comment:
nit: why does it have default value `0` if later you are doing `checkArgument(rateThreshold > 0)` in the constructor? If it's obligatory parameter without a good default value, then I think it would be cleaner to pass it through the constructor to the `AIMDScalingStrategyBuilder`:
```
AIMDScalingStrategyBuilder
.builder(myRateThreshold)
.setOptionalParam1(foo)
.setOptionalParam2(bar)
```
##########
flink-connectors/flink-connector-base/src/main/java/org/apache/flink/connector/base/sink/writer/strategy/RequestInfo.java:
##########
@@ -0,0 +1,67 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.connector.base.sink.writer.strategy;
+
+import org.apache.flink.annotation.PublicEvolving;
+
+import java.time.Instant;
+
+/** Dataclass to encapsulate information about starting requests. */
+@PublicEvolving
+public class RequestInfo {
+ private final int batchSize;
+ private final Instant requestStartTime;
+
+ private RequestInfo(int batchSize, Instant requestStartTime) {
+ this.batchSize = batchSize;
+ this.requestStartTime = requestStartTime;
+ }
+
+ @PublicEvolving
+ public static RequestInfoBuilder builder() {
+ return new RequestInfoBuilder();
+ }
+
+ public int getBatchSize() {
+ return batchSize;
+ }
+
+ public Instant getRequestStartTime() {
+ return requestStartTime;
+ }
+
+ /** Builder for {@link RequestInfo} dataclass. */
+ public static class RequestInfoBuilder {
+ private int batchSize;
+ private Instant requestStartTime;
+
+ public RequestInfoBuilder setBatchSize(final int batchSize) {
+ this.batchSize = batchSize;
+ return this;
+ }
+
+ public RequestInfoBuilder setRequestStartTime(final Instant requestStartTime) {
+ this.requestStartTime = requestStartTime;
+ return this;
+ }
+
+ public RequestInfo build() {
+ return new RequestInfo(batchSize, requestStartTime);
+ }
+ }
Review Comment:
Why do we need a builder for this class? Especially given that both of those parameters seems to be obligatory?
##########
flink-connectors/flink-connector-base/src/main/java/org/apache/flink/connector/base/sink/writer/AsyncSinkWriter.java:
##########
@@ -344,69 +352,69 @@ public void write(InputT element, Context context) throws IOException, Interrupt
* </ul>
*/
private void nonBlockingFlush() throws InterruptedException {
- while (!isInFlightRequestOrMessageLimitExceeded()
+ while (!rateLimitingStrategy.shouldBlock(createRequestInfo())
&& (bufferedRequestEntries.size() >= getNextBatchSizeLimit()
|| bufferedRequestEntriesTotalSizeInBytes >= maxBatchSizeInBytes)) {
flush();
}
}
- /**
- * Determines if the sink should block and complete existing in flight requests before it may
- * prudently create any new ones. This is exactly determined by if the number of requests
- * currently in flight exceeds the maximum supported by the sink OR if the number of in flight
- * messages exceeds the maximum determined to be appropriate by the rate limiting strategy.
- */
- private boolean isInFlightRequestOrMessageLimitExceeded() {
- return inFlightRequestsCount >= maxInFlightRequests
- || inFlightMessages >= rateLimitingStrategy.getRateLimit();
+ private RequestInfo createRequestInfo() {
+ int batchSize = getNextBatchSize();
+ Instant requestStartTime = Instant.now();
+ return RequestInfo.builder()
+ .setBatchSize(batchSize)
+ .setRequestStartTime(requestStartTime)
+ .build();
Review Comment:
I have some doubts if creating new `RequestInfo` per every record is a good idea.
1. Just sheer fact of creating new object might increase GC pressure and add a bit of overhead
2. I would expect `Instant.now();` to be very costly to invoke. Isn't this a syscall underneath? Why do we even need `requestStartTime` in the `RequestInfo`?
And to me it looks like this object is reconstructed over and over again at least once per every `AsyncSinkWriter#write` call?
##########
flink-connectors/flink-connector-base/src/main/java/org/apache/flink/connector/base/sink/writer/strategy/ResultInfo.java:
##########
@@ -0,0 +1,66 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.connector.base.sink.writer.strategy;
+
+import org.apache.flink.annotation.PublicEvolving;
+
+/** Dataclass to encapsulate results from completed requests. */
+@PublicEvolving
+public class ResultInfo {
Review Comment:
Same two questions as in `RequestInfo`:
1. Having a builder with optional setter methods without a sane default values doesn't make sense to me at the first glance.
2. We shouldn't be exposing the concrete class and the builder as `PublicEvolving` API (unless I'm missing something)
##########
flink-connectors/flink-connector-base/src/main/java/org/apache/flink/connector/base/sink/writer/AsyncSinkWriter.java:
##########
@@ -256,14 +243,42 @@ public AsyncSinkWriter(
long maxTimeInBufferMS,
long maxRecordSizeInBytes,
Collection<BufferedRequestState<RequestEntryT>> states) {
+ this(
+ elementConverter,
+ context,
+ maxBatchSize,
+ maxBufferedRequests,
+ maxBatchSizeInBytes,
+ maxTimeInBufferMS,
+ maxRecordSizeInBytes,
+ states,
+ CongestionControlRateLimitingStrategy.builder()
+ .setMaxInFlightRequests(maxInFlightRequests)
+ .setInitialMaxInFlightMessages(maxBatchSize)
+ .setAimdScalingStrategy(
+ AIMDScalingStrategy.builder()
+ .setRateThreshold(maxBatchSize * maxInFlightRequests)
+ .build())
+ .build());
+ }
+
+ public AsyncSinkWriter(
+ ElementConverter<InputT, RequestEntryT> elementConverter,
+ Sink.InitContext context,
+ int maxBatchSize,
+ int maxBufferedRequests,
+ long maxBatchSizeInBytes,
+ long maxTimeInBufferMS,
+ long maxRecordSizeInBytes,
+ Collection<BufferedRequestState<RequestEntryT>> states,
+ RateLimitingStrategy rateLimitingStrategy) {
Review Comment:
Does the `AsyncSinkWriter` have any documentation? How users are supposed to know that it exists and especially what kind of `RateLimitingStrategy` they can use?
##########
flink-connectors/flink-connector-base/src/main/java/org/apache/flink/connector/base/sink/writer/strategy/RequestInfo.java:
##########
@@ -0,0 +1,67 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.connector.base.sink.writer.strategy;
+
+import org.apache.flink.annotation.PublicEvolving;
+
+import java.time.Instant;
+
+/** Dataclass to encapsulate information about starting requests. */
+@PublicEvolving
+public class RequestInfo {
+ private final int batchSize;
+ private final Instant requestStartTime;
+
+ private RequestInfo(int batchSize, Instant requestStartTime) {
+ this.batchSize = batchSize;
+ this.requestStartTime = requestStartTime;
+ }
+
+ @PublicEvolving
+ public static RequestInfoBuilder builder() {
+ return new RequestInfoBuilder();
+ }
Review Comment:
Does user need to know how to construct this class? Shouldn't only a `RequestInfo` interface by `@PublicEvolving` while a concrete implementation by `@Internal` to the `AsyncSinkWriter`?
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