Spring batch partitioning is not working - spring-batch

Question

I am using Spring Batch Partitioning to merge data from group of related flat files to a single file. The batch is failing with below two issues:
First slave step thread is failing as the data to file writer is written before it is opened. The value for variable inputFileNames (step context data provided by partitioner) for this thread is[20002", 20003]
Second slave step thread is failing as the partitioning data is missing from the step context. The value for variable inputFileNames for this thread is null
Please let me know if I am missing some thing in the configuration.
// log with Error info
2015-12-26 17:59:14,165 DEBUG [SimpleAsyncTaskExecutor-1] c.d.d.b.r.ReaderConfiguration [ReaderBatchConfiguration.java:473] inputFileNames ----[20002", 20003]
2015-12-26 17:59:14,165 DEBUG [SimpleAsyncTaskExecutor-1] c.d.d.b.r.BatchConfiguration [BatchConfiguration.java:389] consumer ----p2
2015-12-26 17:59:14,275 ERROR [SimpleAsyncTaskExecutor-1] o.s.b.c.s.AbstractStep [AbstractStep.java:225] Encountered an error executing step testConsumersInputFileMergeStep in job testFileForInputJob
org.springframework.batch.item.WriterNotOpenException: Writer must be open before it can be written to
at org.springframework.batch.item.file.FlatFileItemWriter.write(FlatFileItemWriter.java:255) ~[spring-batch-infrastructure-3.0.3.RELEASE.jar:3.0.3.RELEASE]
2015-12-26 18:00:14,421 DEBUG [SimpleAsyncTaskExecutor-2] c.d.d.b.r.ReaderBatchConfiguration [ReaderConfiguration.java:474] inputFileNames ----null
// Partitioner
public class ProvisioningInputFilePartitioner implements Partitioner {
#Override
public Map<String, ExecutionContext> partition(int gridSize) {
Map<String, ExecutionContext> filesToProcess = getFilesToProcess(outboundSourceFolder);
Map<String, ExecutionContext> execCtxs = new HashMap<>();
for(Entry<String, ExecutionContext> entry : filesToProcess.entrySet()) {
execCtxs.put(entry.getKey(), entry.getValue());
}
return execCtxs;
}
private Map<String, ExecutionContext> getFilesToProcess(String outboundSourceFolder2) {
Map<String, ExecutionContext> contexts = new HashMap<>();
ExecutionContext execCtx1 = new ExecutionContext();
List<String> inputFileNames1 = Arrays.asList("20001", "22222");
execCtx1.put("consumer", "p1");
execCtx1.put("inputFileNames", inputFileNames1);
contexts.put("p1", execCtx1);
ExecutionContext execCtx2 = new ExecutionContext();
List<String> inputFileNames2 = Arrays.asList("20002", "20003");
execCtx1.put("consumer", "p2");
execCtx1.put("inputFileNames", inputFileNames2);
contexts.put("p2", execCtx2);
return contexts;
}
}
// Writer
#Bean
#StepScope
public ItemWriter<String> testConsumerFileItemWriter (#Value("#{stepExecutionContext[consumer]}") String consumer){
logger.debug("consumer ----"+ consumer);
FileSystemResource fileSystemResource = new FileSystemResource(new File(outboundSourceFolder, consumer + ".txt"));
FlatFileItemWriter<String> fileItemWriter = new FlatFileItemWriter<>();
fileItemWriter.setResource(fileSystemResource);
fileItemWriter.setLineAggregator(new PassThroughLineAggregator<String>());
return fileItemWriter;
}
#Bean
public Partitioner provisioningInputFilePartitioner() {
return new ProvisioningInputFilePartitioner();
}
#Bean
public TaskExecutor taskExecutor() {
return new SimpleAsyncTaskExecutor();
}
// Reader
#Bean
#StepScope
public ItemReader<String> testInputFilesReader (#Value("#{stepExecutionContext[inputFileNames]}") List<String> inputFileNames) {
logger.debug("inputFileNames ----" + inputFileNames);
MultiResourceItemReader<String> multiResourceItemReader = new MultiResourceItemReader<String>();
...
return multiResourceItemReader;
}
// slave step
#Bean
public Step testConsumersInputFileMergeStep(StepBuilderFactory stepBuilder, ItemReader<String> testInputFilesReader,
ItemWriter<String> testConsumerFileItemWriter){
return stepBuilder.get("testConsumersInputFileMergeStep").<String, String>chunk(1).reader(testInputFilesReader)
.writer(testConsumerFileItemWriter).build();
}
// master step
#Bean
public Step testConsumersFilePartitionerStep(StepBuilderFactory stepBuilder, Step testConsumersInputFileMergeStep, Partitioner provisioningInputFilePartitioner,
TaskExecutor taskExecutor ){
return stepBuilder.get("testConsumersFilePartitionerStep").partitioner(testConsumersInputFileMergeStep)
.partitioner("testConsumersInputFileMergeStep", provisioningInputFilePartitioner)
.taskExecutor(taskExecutor)
.build();
}
//Job
#Bean
public Job testFileForInputJob(JobBuilderFactory factory, Step testFileForInputStep, Step testConsumersFilePartitionerStep) {
return factory.get("testFileForInputJob").incrementer(new RunIdIncrementer()).start(testConsumersFilePartitionerStep).build();
}