Hi Dian,
Thanks for the reminder. Yes, the original udf implementation does not
qualify the input and output type requirement. After adding a unit test, I
was able to find what's wrong, and fix my UDF implementation. Here is the
new implementation FYI.
@udf(result_type=DataTypes.DOUBLE(), func_type="pandas")
def predict(users, items):
n_users, n_items = 943, 1682
model = MatrixFactorization(n_users, n_items)
model.load_state_dict(torch.load("model.pth"))
return pd.Series(model(users, items).detach().numpy())
And here is the unit test.
def test_predict():
f = predict._func
users = pd.Series([1, 2, 3])
items = pd.Series([1, 4, 9])
preds = f(users, items)
assert isinstance(preds, pd.Series)
assert len(preds) == 3
Thank you so much!
Best,
Yik San
On Wed, Apr 14, 2021 at 11:03 PM Dian Fu <[email protected]> wrote:
> Hi Yik San,
>
> 1) There are two kinds of Python UDFs in PyFlink:
> - General Python UDFs which process input elements at row basis. That is,
> it will process one row at a time.
> - Pandas UDFs which process input elements at batch basis.
> So you are correct that you need to use Pandas UDF for your requirements.
>
> 2) For Pandas UDF, the input type for each input argument is Pandas.Series
> and the result type should also be a Pandas.Series. Besides, the length of
> the result should be the same as the inputs. Could you check if this is the
> case for your Pandas UDF implementation?
>
> Regards,
> Dian
>
>
> On Wed, Apr 14, 2021 at 9:44 PM Yik San Chan <[email protected]>
> wrote:
>
>> The question is cross-posted on Stack Overflow
>> https://stackoverflow.com/questions/67092978/pyflink-vectorized-udf-throws-nullpointerexception
>> .
>>
>> I have a ML model that takes two numpy.ndarray - `users` and `items` -
>> and returns an numpy.ndarray `predictions`. In normal Python code, I would
>> do:
>>
>> ```python
>> model = load_model()
>>
>> df = load_data() # the DataFrame includes 4 columns, namely, user_id,
>> movie_id, rating, and timestamp
>>
>> users = df.user_id.values
>> items = df.movie_id.values
>>
>> predictions = model(users, items)
>> ```
>>
>> I am looking into porting this code into Flink to leverage its
>> distributed nature. My assumption is: by distributing the prediction
>> workload on multiple Flink nodes, I should be able to run the whole
>> prediction faster.
>>
>> So I compose a PyFlink job. Note I implement an UDF called `predict` to
>> run the prediction.
>>
>> ```python
>> # batch_prediction.py
>>
>> model = load_model()
>>
>> settings = EnvironmentSettings.new_instance().use_blink_planner().build()
>> exec_env = StreamExecutionEnvironment.get_execution_environment()
>> t_env = StreamTableEnvironment.create(exec_env,
>> environment_settings=settings)
>>
>> SOURCE_DDL = """
>> CREATE TABLE source (
>> user_id INT,
>> movie_id INT,
>> rating TINYINT,
>> event_ms BIGINT
>> ) WITH (
>> 'connector' = 'filesystem',
>> 'format' = 'csv',
>> 'csv.field-delimiter' = '\t',
>> 'path' = 'ml-100k/u1.test'
>> )
>> """
>>
>> SINK_DDL = """
>> CREATE TABLE sink (
>> prediction DOUBLE
>> ) WITH (
>> 'connector' = 'print'
>> )
>> """
>>
>> t_env.execute_sql(SOURCE_DDL)
>> t_env.execute_sql(SINK_DDL)
>> t_env.execute_sql(
>> "INSERT INTO sink SELECT PREDICT(user_id, movie_id) FROM source"
>> ).wait()
>> ```
>>
>> Here is the UDF.
>>
>> ```python
>> # batch_prediction.py (cont)
>>
>> @udf(result_type=DataTypes.DOUBLE())
>> def predict(user, item):
>> return model([user], [item]).item()
>>
>> t_env.create_temporary_function("predict", predict)
>> ```
>>
>> The job runs fine. However, the prediction actually runs on each and
>> every row of the `source` table, which is not performant. Instead, I want
>> to split the 80,000 (user_id, movie_id) pairs into, let's say, 100 batches,
>> with each batch having 800 rows. The job triggers the `model(users, items)`
>> function 100 times (= # of batch), where both `users` and `items` have 800
>> elements.
>>
>> I couldn't find a way to do this. By looking at the [docs](
>> https://ci.apache.org/projects/flink/flink-docs-stable/dev/python/table-api-users-guide/udfs/vectorized_python_udfs.html),
>> vectorized user-defined functions may work.
>>
>> ```python
>> # batch_prediction.py (snippet)
>>
>> # I add the func_type="pandas"
>> @udf(result_type=DataTypes.DOUBLE(), func_type="pandas")
>> def predict(user, item):
>> ...
>> ```
>>
>> Unfortunately, it doesn't.
>>
>> ```
>> > python batch_prediction.py
>> ...
>> Traceback (most recent call last):
>> File "batch_prediction.py", line 55, in <module>
>> "INSERT INTO sink SELECT PREDICT(user_id, movie_id) FROM source"
>> File
>> "/usr/local/anaconda3/envs/flink-ml/lib/python3.7/site-packages/pyflink/table/table_result.py",
>> line 76, in wait
>> get_method(self._j_table_result, "await")()
>> File
>> "/usr/local/anaconda3/envs/flink-ml/lib/python3.7/site-packages/py4j/java_gateway.py",
>> line 1286, in __call__
>> answer, self.gateway_client, self.target_id, self.name)
>> File
>> "/usr/local/anaconda3/envs/flink-ml/lib/python3.7/site-packages/pyflink/util/exceptions.py",
>> line 147, in deco
>> return f(*a, **kw)
>> File
>> "/usr/local/anaconda3/envs/flink-ml/lib/python3.7/site-packages/py4j/protocol.py",
>> line 328, in get_return_value
>> format(target_id, ".", name), value)
>> py4j.protocol.Py4JJavaError: An error occurred while calling o51.await.
>> : java.util.concurrent.ExecutionException:
>> org.apache.flink.table.api.TableException: Failed to wait job finish
>> at
>> java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:357)
>> at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1908)
>> at
>> org.apache.flink.table.api.internal.TableResultImpl.awaitInternal(TableResultImpl.java:119)
>> at
>> org.apache.flink.table.api.internal.TableResultImpl.await(TableResultImpl.java:86)
>> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>> at
>> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
>> at
>> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>> at java.lang.reflect.Method.invoke(Method.java:498)
>> at
>> org.apache.flink.api.python.shaded.py4j.reflection.MethodInvoker.invoke(MethodInvoker.java:244)
>> at
>> org.apache.flink.api.python.shaded.py4j.reflection.ReflectionEngine.invoke(ReflectionEngine.java:357)
>> at
>> org.apache.flink.api.python.shaded.py4j.Gateway.invoke(Gateway.java:282)
>> at
>> org.apache.flink.api.python.shaded.py4j.commands.AbstractCommand.invokeMethod(AbstractCommand.java:132)
>> at
>> org.apache.flink.api.python.shaded.py4j.commands.CallCommand.execute(CallCommand.java:79)
>> at
>> org.apache.flink.api.python.shaded.py4j.GatewayConnection.run(GatewayConnection.java:238)
>> at java.lang.Thread.run(Thread.java:748)
>> Caused by: org.apache.flink.table.api.TableException: Failed to wait job
>> finish
>> at
>> org.apache.flink.table.api.internal.InsertResultIterator.hasNext(InsertResultIterator.java:59)
>> at
>> org.apache.flink.table.api.internal.TableResultImpl$CloseableRowIteratorWrapper.hasNext(TableResultImpl.java:355)
>> at
>> org.apache.flink.table.api.internal.TableResultImpl$CloseableRowIteratorWrapper.isFirstRowReady(TableResultImpl.java:368)
>> at
>> org.apache.flink.table.api.internal.TableResultImpl.lambda$awaitInternal$1(TableResultImpl.java:107)
>> at
>> java.util.concurrent.CompletableFuture$AsyncRun.run(CompletableFuture.java:1640)
>> at
>> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
>> at
>> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
>> ... 1 more
>> Caused by: java.util.concurrent.ExecutionException:
>> org.apache.flink.runtime.client.JobExecutionException: Job execution failed.
>> at
>> java.util.concurrent.CompletableFuture.reportGet(CompletableFuture.java:357)
>> at java.util.concurrent.CompletableFuture.get(CompletableFuture.java:1908)
>> at
>> org.apache.flink.table.api.internal.InsertResultIterator.hasNext(InsertResultIterator.java:57)
>> ... 7 more
>> Caused by: org.apache.flink.runtime.client.JobExecutionException: Job
>> execution failed.
>> at
>> org.apache.flink.runtime.jobmaster.JobResult.toJobExecutionResult(JobResult.java:147)
>> at
>> org.apache.flink.runtime.minicluster.MiniClusterJobClient.lambda$getJobExecutionResult$2(MiniClusterJobClient.java:119)
>> at
>> java.util.concurrent.CompletableFuture.uniApply(CompletableFuture.java:616)
>> at
>> java.util.concurrent.CompletableFuture$UniApply.tryFire(CompletableFuture.java:591)
>> at
>> java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:488)
>> at
>> java.util.concurrent.CompletableFuture.complete(CompletableFuture.java:1975)
>> at
>> org.apache.flink.runtime.rpc.akka.AkkaInvocationHandler.lambda$invokeRpc$0(AkkaInvocationHandler.java:229)
>> at
>> java.util.concurrent.CompletableFuture.uniWhenComplete(CompletableFuture.java:774)
>> at
>> java.util.concurrent.CompletableFuture$UniWhenComplete.tryFire(CompletableFuture.java:750)
>> at
>> java.util.concurrent.CompletableFuture.postComplete(CompletableFuture.java:488)
>> at
>> java.util.concurrent.CompletableFuture.complete(CompletableFuture.java:1975)
>> at
>> org.apache.flink.runtime.concurrent.FutureUtils$1.onComplete(FutureUtils.java:996)
>> at akka.dispatch.OnComplete.internal(Future.scala:264)
>> at akka.dispatch.OnComplete.internal(Future.scala:261)
>> at akka.dispatch.japi$CallbackBridge.apply(Future.scala:191)
>> at akka.dispatch.japi$CallbackBridge.apply(Future.scala:188)
>> at scala.concurrent.impl.CallbackRunnable.run(Promise.scala:36)
>> at
>> org.apache.flink.runtime.concurrent.Executors$DirectExecutionContext.execute(Executors.java:74)
>> at
>> scala.concurrent.impl.CallbackRunnable.executeWithValue(Promise.scala:44)
>> at
>> scala.concurrent.impl.Promise$DefaultPromise.tryComplete(Promise.scala:252)
>> at akka.pattern.PromiseActorRef.$bang(AskSupport.scala:572)
>> at
>> akka.pattern.PipeToSupport$PipeableFuture$$anonfun$pipeTo$1.applyOrElse(PipeToSupport.scala:22)
>> at
>> akka.pattern.PipeToSupport$PipeableFuture$$anonfun$pipeTo$1.applyOrElse(PipeToSupport.scala:21)
>> at scala.concurrent.Future$$anonfun$andThen$1.apply(Future.scala:436)
>> at scala.concurrent.Future$$anonfun$andThen$1.apply(Future.scala:435)
>> at scala.concurrent.impl.CallbackRunnable.run(Promise.scala:36)
>> at
>> akka.dispatch.BatchingExecutor$AbstractBatch.processBatch(BatchingExecutor.scala:55)
>> at
>> akka.dispatch.BatchingExecutor$BlockableBatch$$anonfun$run$1.apply$mcV$sp(BatchingExecutor.scala:91)
>> at
>> akka.dispatch.BatchingExecutor$BlockableBatch$$anonfun$run$1.apply(BatchingExecutor.scala:91)
>> at
>> akka.dispatch.BatchingExecutor$BlockableBatch$$anonfun$run$1.apply(BatchingExecutor.scala:91)
>> at scala.concurrent.BlockContext$.withBlockContext(BlockContext.scala:72)
>> at
>> akka.dispatch.BatchingExecutor$BlockableBatch.run(BatchingExecutor.scala:90)
>> at akka.dispatch.TaskInvocation.run(AbstractDispatcher.scala:40)
>> at
>> akka.dispatch.ForkJoinExecutorConfigurator$AkkaForkJoinTask.exec(ForkJoinExecutorConfigurator.scala:44)
>> at akka.dispatch.forkjoin.ForkJoinTask.doExec(ForkJoinTask.java:260)
>> at
>> akka.dispatch.forkjoin.ForkJoinPool$WorkQueue.runTask(ForkJoinPool.java:1339)
>> at akka.dispatch.forkjoin.ForkJoinPool.runWorker(ForkJoinPool.java:1979)
>> at
>> akka.dispatch.forkjoin.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:107)
>> Caused by: org.apache.flink.runtime.JobException: Recovery is suppressed
>> by NoRestartBackoffTimeStrategy
>> at
>> org.apache.flink.runtime.executiongraph.failover.flip1.ExecutionFailureHandler.handleFailure(ExecutionFailureHandler.java:116)
>> at
>> org.apache.flink.runtime.executiongraph.failover.flip1.ExecutionFailureHandler.getFailureHandlingResult(ExecutionFailureHandler.java:78)
>> at
>> org.apache.flink.runtime.scheduler.DefaultScheduler.handleTaskFailure(DefaultScheduler.java:224)
>> at
>> org.apache.flink.runtime.scheduler.DefaultScheduler.maybeHandleTaskFailure(DefaultScheduler.java:217)
>> at
>> org.apache.flink.runtime.scheduler.DefaultScheduler.updateTaskExecutionStateInternal(DefaultScheduler.java:208)
>> at
>> org.apache.flink.runtime.scheduler.SchedulerBase.updateTaskExecutionState(SchedulerBase.java:610)
>> at
>> org.apache.flink.runtime.scheduler.SchedulerNG.updateTaskExecutionState(SchedulerNG.java:89)
>> at
>> org.apache.flink.runtime.jobmaster.JobMaster.updateTaskExecutionState(JobMaster.java:419)
>> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>> at
>> sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
>> at
>> sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
>> at java.lang.reflect.Method.invoke(Method.java:498)
>> at
>> org.apache.flink.runtime.rpc.akka.AkkaRpcActor.handleRpcInvocation(AkkaRpcActor.java:286)
>> at
>> org.apache.flink.runtime.rpc.akka.AkkaRpcActor.handleRpcMessage(AkkaRpcActor.java:201)
>> at
>> org.apache.flink.runtime.rpc.akka.FencedAkkaRpcActor.handleRpcMessage(FencedAkkaRpcActor.java:74)
>> at
>> org.apache.flink.runtime.rpc.akka.AkkaRpcActor.handleMessage(AkkaRpcActor.java:154)
>> at akka.japi.pf.UnitCaseStatement.apply(CaseStatements.scala:26)
>> at akka.japi.pf.UnitCaseStatement.apply(CaseStatements.scala:21)
>> at scala.PartialFunction$class.applyOrElse(PartialFunction.scala:123)
>> at akka.japi.pf.UnitCaseStatement.applyOrElse(CaseStatements.scala:21)
>> at scala.PartialFunction$OrElse.applyOrElse(PartialFunction.scala:170)
>> at scala.PartialFunction$OrElse.applyOrElse(PartialFunction.scala:171)
>> at scala.PartialFunction$OrElse.applyOrElse(PartialFunction.scala:171)
>> at akka.actor.Actor$class.aroundReceive(Actor.scala:517)
>> at akka.actor.AbstractActor.aroundReceive(AbstractActor.scala:225)
>> at akka.actor.ActorCell.receiveMessage(ActorCell.scala:592)
>> at akka.actor.ActorCell.invoke(ActorCell.scala:561)
>> at akka.dispatch.Mailbox.processMailbox(Mailbox.scala:258)
>> at akka.dispatch.Mailbox.run(Mailbox.scala:225)
>> at akka.dispatch.Mailbox.exec(Mailbox.scala:235)
>> ... 4 more
>> Caused by:
>> org.apache.flink.streaming.runtime.tasks.AsynchronousException: Caught
>> exception while processing timer.
>> at
>> org.apache.flink.streaming.runtime.tasks.StreamTask$StreamTaskAsyncExceptionHandler.handleAsyncException(StreamTask.java:1108)
>> at
>> org.apache.flink.streaming.runtime.tasks.StreamTask.handleAsyncException(StreamTask.java:1082)
>> at
>> org.apache.flink.streaming.runtime.tasks.StreamTask.invokeProcessingTimeCallback(StreamTask.java:1213)
>> at
>> org.apache.flink.streaming.runtime.tasks.StreamTask.lambda$null$17(StreamTask.java:1202)
>> at
>> org.apache.flink.streaming.runtime.tasks.StreamTaskActionExecutor$SynchronizedStreamTaskActionExecutor.runThrowing(StreamTaskActionExecutor.java:92)
>> at org.apache.flink.streaming.runtime.tasks.mailbox.Mail.run(Mail.java:78)
>> at
>> org.apache.flink.streaming.runtime.tasks.mailbox.MailboxExecutorImpl.tryYield(MailboxExecutorImpl.java:91)
>> at
>> org.apache.flink.streaming.runtime.tasks.StreamOperatorWrapper.quiesceTimeServiceAndCloseOperator(StreamOperatorWrapper.java:155)
>> at
>> org.apache.flink.streaming.runtime.tasks.StreamOperatorWrapper.close(StreamOperatorWrapper.java:130)
>> at
>> org.apache.flink.streaming.runtime.tasks.OperatorChain.closeOperators(OperatorChain.java:412)
>> at
>> org.apache.flink.streaming.runtime.tasks.StreamTask.afterInvoke(StreamTask.java:585)
>> at
>> org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:547)
>> at org.apache.flink.runtime.taskmanager.Task.doRun(Task.java:722)
>> at org.apache.flink.runtime.taskmanager.Task.run(Task.java:547)
>> at java.lang.Thread.run(Thread.java:748)
>> Caused by: TimerException{java.lang.RuntimeException: Failed to close
>> remote bundle}
>> ... 13 more
>> Caused by: java.lang.RuntimeException: Failed to close remote bundle
>> at
>> org.apache.flink.streaming.api.runners.python.beam.BeamPythonFunctionRunner.finishBundle(BeamPythonFunctionRunner.java:371)
>> at
>> org.apache.flink.streaming.api.runners.python.beam.BeamPythonFunctionRunner.flush(BeamPythonFunctionRunner.java:325)
>> at
>> org.apache.flink.streaming.api.operators.python.AbstractPythonFunctionOperator.invokeFinishBundle(AbstractPythonFunctionOperator.java:291)
>> at
>> org.apache.flink.table.runtime.operators.python.scalar.arrow.RowDataArrowPythonScalarFunctionOperator.invokeFinishBundle(RowDataArrowPythonScalarFunctionOperator.java:77)
>> at
>> org.apache.flink.streaming.api.operators.python.AbstractPythonFunctionOperator.checkInvokeFinishBundleByTime(AbstractPythonFunctionOperator.java:285)
>> at
>> org.apache.flink.streaming.api.operators.python.AbstractPythonFunctionOperator.lambda$open$0(AbstractPythonFunctionOperator.java:134)
>> at
>> org.apache.flink.streaming.runtime.tasks.StreamTask.invokeProcessingTimeCallback(StreamTask.java:1211)
>> ... 12 more
>> Caused by: java.lang.NullPointerException
>> at
>> org.apache.flink.streaming.api.runners.python.beam.BeamPythonFunctionRunner.finishBundle(BeamPythonFunctionRunner.java:369)
>> ... 18 more
>> ```
>>
>> The error messages are not very helpful. Can anyone help? Thanks!
>>
>> Note: source code can be found [here](
>> https://github.com/YikSanChan/flink-torch/tree/83ea0510172db3d7ff33db19883150f2fe5c1f43).
>> To run the code, you will need Anaconda locally, then:
>>
>> ```
>> conda env create -f environment.yml
>> conda activate flink-ml
>> ```
>>
>> Best,
>> Yik San
>>
>
