[GitHub] [flink] WeiZhong94 commented on a change in pull request #9653: [FLINK-14014][python] Introduce PythonScalarFunctionRunner to handle the communication with Python worker for Python ScalarFunction execution

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WeiZhong94 commented on a change in pull request #9653: [FLINK-14014][python] Introduce PythonScalarFunctionRunner to handle the communication with Python worker for Python ScalarFunction execution
URL: https://github.com/apache/flink/pull/9653#discussion_r325458729
 
 

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 File path: flink-python/src/main/java/org/apache/flink/python/AbstractPythonFunctionRunner.java
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+/*
+ * 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.python;
+
+import org.apache.flink.annotation.Internal;
+import org.apache.flink.core.memory.ByteArrayInputStreamWithPos;
+import org.apache.flink.core.memory.ByteArrayOutputStreamWithPos;
+import org.apache.flink.table.functions.python.PythonEnv;
+import org.apache.flink.util.Preconditions;
+
+import org.apache.beam.model.pipeline.v1.RunnerApi;
+import org.apache.beam.runners.core.construction.Environments;
+import org.apache.beam.runners.core.construction.PipelineOptionsTranslation;
+import org.apache.beam.runners.core.construction.graph.ExecutableStage;
+import org.apache.beam.runners.fnexecution.control.BundleProgressHandler;
+import org.apache.beam.runners.fnexecution.control.DefaultJobBundleFactory;
+import org.apache.beam.runners.fnexecution.control.JobBundleFactory;
+import org.apache.beam.runners.fnexecution.control.OutputReceiverFactory;
+import org.apache.beam.runners.fnexecution.control.RemoteBundle;
+import org.apache.beam.runners.fnexecution.control.StageBundleFactory;
+import org.apache.beam.runners.fnexecution.provisioning.JobInfo;
+import org.apache.beam.runners.fnexecution.state.StateRequestHandler;
+import org.apache.beam.sdk.coders.Coder;
+import org.apache.beam.sdk.fn.data.FnDataReceiver;
+import org.apache.beam.sdk.options.PipelineOptionsFactory;
+import org.apache.beam.sdk.options.PortablePipelineOptions;
+import org.apache.beam.sdk.util.WindowedValue;
+import org.apache.beam.vendor.grpc.v1p21p0.com.google.protobuf.Struct;
+
+import java.io.DataOutputStream;
+import java.io.File;
+import java.io.FileOutputStream;
+import java.nio.file.Files;
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * An base class for {@link PythonFunctionRunner}.
+ *
+ * @param <IN> Type of the input elements.
+ * @param <OUT> Type of the execution results.
+ */
+@Internal
+public abstract class AbstractPythonFunctionRunner<IN, OUT> implements PythonFunctionRunner<IN> {
+
+	private static final String MAIN_INPUT_ID = "input";
+
+	private final String taskName;
+
+	/**
+	 * The Python function execution result receiver.
+	 */
+	private final FnDataReceiver<OUT> resultReceiver;
+
+	/**
+	 * The Python execution environment.
+	 */
+	private final PythonEnv pythonEnv;
+
+	/**
+	 * The bundle factory which has all job-scoped information and can be used to create a {@link StageBundleFactory}.
+	 */
+	private transient JobBundleFactory jobBundleFactory;
+
+	/**
+	 * The bundle factory which has all of the resources it needs to provide new {@link RemoteBundle}.
+	 */
+	private transient StageBundleFactory stageBundleFactory;
+
+	/**
+	 * Handler for state requests.
+	 */
+	private final StateRequestHandler stateRequestHandler;
+
+	/**
+	 * Handler for bundle progress messages, both during bundle execution and on its completion.
+	 */
+	private transient BundleProgressHandler progressHandler;
+
+	/**
+	 * A bundle handler for handling input elements by forwarding them to a remote environment for processing.
+	 * It holds a collection of {@link FnDataReceiver}s which actually perform the data forwarding work.
+	 *
+	 * <p>When a RemoteBundle is closed, it will block until bundle processing is finished on remote resources,
+	 * and throw an exception if bundle processing has failed.
+	 */
+	private transient RemoteBundle remoteBundle;
+
+	/**
+	 * The receiver which forwards the input elements to a remote environment for processing.
+	 */
+	private transient FnDataReceiver<WindowedValue<?>> mainInputReceiver;
+
+	/**
+	 * The coder for input elements.
+	 */
+	private transient Coder<IN> inputCoder;
+
+	/**
+	 * The coder for execution results.
+	 */
+	private transient Coder<OUT> outputCoder;
+
+	/**
+	 * Reusable InputStream used to holding the execution results to be deserialized.
+	 */
+	private transient ByteArrayInputStreamWithPos bais;
+
+	/**
+	 * Reusable OutputStream used to holding the serialized input elements.
+	 */
+	private transient ByteArrayOutputStreamWithPos baos;
+
+	public AbstractPythonFunctionRunner(
+		String taskName,
+		FnDataReceiver<OUT> resultReceiver,
+		PythonEnv pythonEnv,
+		StateRequestHandler stateRequestHandler) {
+		this.taskName = Preconditions.checkNotNull(taskName);
+		this.resultReceiver = Preconditions.checkNotNull(resultReceiver);
+		this.pythonEnv = Preconditions.checkNotNull(pythonEnv);
+		this.stateRequestHandler = Preconditions.checkNotNull(stateRequestHandler);
+	}
+
+	@Override
+	public void open() throws Exception {
+		bais = new ByteArrayInputStreamWithPos();
+		baos = new ByteArrayOutputStreamWithPos();
+		inputCoder = getInputCoder();
+		outputCoder = getOutputCoder();
+
+		PortablePipelineOptions portableOptions =
+			PipelineOptionsFactory.as(PortablePipelineOptions.class);
+		// one operator has one Python SDK harness
+		portableOptions.setSdkWorkerParallelism(1);
+		Struct pipelineOptions = PipelineOptionsTranslation.toProto(portableOptions);
+
+		jobBundleFactory = createJobBundleFactory(pipelineOptions);
+		stageBundleFactory = jobBundleFactory.forStage(createExecutableStage());
+		progressHandler = BundleProgressHandler.ignored();
+	}
+
+	@Override
+	public void close() throws Exception {
+		try {
+			jobBundleFactory.close();
+		} finally {
+			jobBundleFactory = null;
+		}
+	}
+
+	@Override
+	public void startBundle() {
+		OutputReceiverFactory receiverFactory =
+			new OutputReceiverFactory() {
+
+				// the input value type is always byte array
+				@SuppressWarnings("unchecked")
+				@Override
+				public FnDataReceiver<WindowedValue<byte[]>> create(String pCollectionId) {
+					return input -> {
+						bais.setBuffer(input.getValue(), 0, input.getValue().length);
+						resultReceiver.accept(outputCoder.decode(bais));
+					};
+				}
+			};
+
+		try {
+			remoteBundle = stageBundleFactory.getBundle(receiverFactory, stateRequestHandler, progressHandler);
+			mainInputReceiver =
+				Preconditions.checkNotNull(
+					remoteBundle.getInputReceivers().get(MAIN_INPUT_ID),
+					"Failed to retrieve main input receiver.");
+		} catch (Throwable t) {
+			throw new RuntimeException("Failed to start remote bundle", t);
+		}
+	}
+
+	@Override
+	public void finishBundle() {
+		try {
+			remoteBundle.close();
+		} catch (Throwable t) {
+			throw new RuntimeException("Failed to close remote bundle", t);
+		} finally {
+			remoteBundle = null;
+		}
+	}
+
+	@Override
+	public void processElement(IN element) {
+		try {
+			baos.reset();
+			inputCoder.encode(element, baos);
+			// TODO: support to use ValueOnlyWindowedValueCoder for better performance.
+			// Currently, FullWindowedValueCoder has to be used in Beam's portability framework.
+			mainInputReceiver.accept(WindowedValue.valueInGlobalWindow(baos.toByteArray()));
+		} catch (Throwable t) {
+			throw new RuntimeException("Failed to process element when sending data to Python SDK harness.", t);
+		}
+	}
+
+	public JobBundleFactory createJobBundleFactory(Struct pipelineOptions) throws Exception {
+		return DefaultJobBundleFactory.create(
+			JobInfo.create(taskName, taskName, createEmptyRetrievalToken(), pipelineOptions));
+	}
+
+	/**
+	 * Creates a specification which specifies the portability Python execution environment.
+	 * It's used by Beam's portability framework to creates the actual Python execution environment.
+	 */
+	protected RunnerApi.Environment createPythonExecutionEnvironment() {
+		if (pythonEnv.getExecType() == PythonEnv.ExecType.PROCESS) {
+			final Map<String, String> env = new HashMap<>(2);
+			env.put("python", pythonEnv.getPythonExec());
+
+			return Environments.createProcessEnvironment(
+				"",
+				"",
+				pythonEnv.getPythonWorkerCmd(),
+				env);
+		} else {
+			throw new UnsupportedOperationException(String.format(
+				"Execution type '%s' is not supported.", pythonEnv.getExecType()));
+		}
+	}
+
+	/**
+	 * Creates a {@link ExecutableStage} which contains the Python user-defined functions to be executed
+	 * and all the other information needed to execute them, such as the execution environment, the input
+	 * and output coder, etc.
+	 */
+	public abstract ExecutableStage createExecutableStage();
+
+	/**
+	 * Returns the coder for input elements.
+	 */
+	public abstract Coder<IN> getInputCoder();
+
+	/**
+	 * Returns the coder for execution results.
+	 */
+	public abstract Coder<OUT> getOutputCoder();
+
+	private String createEmptyRetrievalToken() throws Exception {
+		final File retrievalToken = Files.createTempFile("retrieval_token", "json").toFile();
 
 Review comment:
   If this part is running in TaskManager, the better locations to store temporary files is `getContainingTask().getEnvironment().getTaskManagerInfo().getTmpDirectories()`. And maybe we should delete it after finish bundle? At least we should call `retrievalToken.deleteOnExit()` to ensure that it will be deleted when jvm exits.

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