We have few jobs scheduled on data loader, we are receiving the error in the sdl.log file:
Expected 5000 to be processed for batch but got results for 4000

Relevant portion log is given below
 

2016-10-17 10:00:43,681 INFO  [OrderLineItemUpsert] progress.NihilistProgressAdapter setSubTask (NihilistProgressAdapter.java:78) - Processed 1,361,110 of 1,399,110 total records. Rate: -298,000 records per hour. Estimated time to complete: 39 minutes and 13 seconds.  There are 871,232 successes and 489,878 errors.
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2016-10-17 10:00:53,853 INFO  [OrderLineItemUpsert] visitor.BulkApiVisitorUtil updateJobStatus (BulkApiVisitorUtil.java:179) - Batch Status: 0 Queued, 3 In Progress, 249 Completed, 28 Failed.
2016-10-17 10:03:36,748 INFO  [OrderLineItemUpsert] progress.NihilistProgressAdapter setSubTask (NihilistProgressAdapter.java:78) - Processed 1,364,110 of 1,399,110 total records. Rate: -283,000 records per hour. Estimated time to complete: 40 minutes and 38 seconds.  There are 873,972 successes and 490,138 errors.
2016-10-17 10:03:36,748 INFO  [OrderLineItemUpsert] visitor.BulkApiVisitorUtil updateJobStatus (BulkApiVisitorUtil.java:179) - Batch Status: 0 Queued, 0 In Progress, 251 Completed, 29 Failed.
2016-10-17 10:03:36,748 INFO  [OrderLineItemUpsert] progress.NihilistProgressAdapter setSubTask (NihilistProgressAdapter.java:78) - Retrieving Bulk Job Results
2016-10-17 10:03:38,029 ERROR [OrderLineItemUpsert] action.AbstractAction handleException (AbstractAction.java:199) - Exception occured during loading
com.salesforce.dataloader.exception.LoadException: 7511A000007OurvQAC: Expected 5000 to be processed for batch but got results for 4000
    at com.salesforce.dataloader.action.visitor.BulkLoadVisitor.sanityCheckError(BulkLoadVisitor.java:436)
    at com.salesforce.dataloader.action.visitor.BulkLoadVisitor.sanityCheckBatch(BulkLoadVisitor.java:424)
    at com.salesforce.dataloader.action.visitor.BulkLoadVisitor.processResults(BulkLoadVisitor.java:305)
    at com.salesforce.dataloader.action.visitor.BulkLoadVisitor.getResults(BulkLoadVisitor.java:292)
    at com.salesforce.dataloader.action.visitor.BulkLoadVisitor.flushRemaining(BulkLoadVisitor.java:270)
    at com.salesforce.dataloader.action.AbstractLoadAction.flush(AbstractLoadAction.java:86)
    at com.salesforce.dataloader.action.AbstractAction.execute(AbstractAction.java:126)
    at com.salesforce.dataloader.controller.Controller.executeAction(Controller.java:120)
    at com.salesforce.dataloader.process.ProcessRunner.run(ProcessRunner.java:149)
    at com.salesforce.dataloader.process.ProcessRunner.run(ProcessRunner.java:100)
    at com.salesforce.dataloader.process.ProcessRunner.main(ProcessRunner.java:253)
2016-10-17 10:03:38,045 ERROR [OrderLineItemUpsert] progress.NihilistProgressAdapter doneError (NihilistProgressAdapter.java:58) - 7511A000007OurvQAC: Expected 5000 to be processed for batch but got results for 4000

It appears the data loader was running successfully but throws error suddenly and Error/Success files show not record nor they are updated in the system. I have not come across that kind of an error before, any idea or help from the community would be appreciated.