container/src/main/java/com/streamsets/datacollector/runner/SourcePipe.java
public void process(
    Map<String, String> offsets,
    int batchSize,
    ReportErrorDelegate reportErrorDelegate
  ) throws StageException, PipelineRuntimeException {
    this.reportErrorDelegate = reportErrorDelegate;
    getStage().setReportErrorDelegate(this);

    try {
      MDC.put(LogConstants.STAGE, getStage().getInfo().getInstanceName());
      getStage().execute(offsets, batchSize);
    } finally {
      MDC.put(LogConstants.STAGE, "");
    }
  }
public void process(
    Map<String, String> offsets,
    int batchSize,
    ReportErrorDelegate reportErrorDelegate
  ) throws StageException, PipelineRuntimeException {
    this.reportErrorDelegate = reportErrorDelegate;
    getStage().setReportErrorDelegate(this);

    try {
      MDC.put(LogConstants.STAGE, getStage().getInfo().getInstanceName());
      getStage().execute(offsets, batchSize);
    } finally {
      MDC.put(LogConstants.STAGE, "");
    }
  }
Process method for Push source that will give control of the execution to the origin.

@param offsets Offsets from last execution
@param batchSize Maximal configured batch size