Replaying processing of a restarted application

A computer program product for enabling a replay of a processing of at least one data set by a restarted application, the computer program product comprising a computer readable storage medium having program instructions embodied therewith, wherein the computer readable storage medium is not a transitory signal per se, the program instructions executable by a processor to cause the processor to perform a method comprising:

• establishing, by the processor, a predetermined checkpoint and storing a log of duplicate read data in association with the predetermined checkpoint during a running of an application that is processing at least one data set, the duplicate read data including an image of all data retrieved from the at least one data set in response to a plurality of data reads made by the application before the predetermined checkpoint;
• identifying, by the processor, a first failure of the application;
• and
• restarting, by the processor, the application and performing a first replay of the application in response to the first failure, including:
• identifying, by the processor, a first plurality of data reads from the restarted application that occur before the predetermined checkpoint,
• returning, by the processor, the duplicate read data to the restarted application, in response to the first plurality of data reads,
• identifying, by the processor, a first plurality of data writes from the application, where the first plurality of data writes include writes made by the application before the predetermined checkpoint,
• discarding, by the processor, the first plurality of data writes by writing the first plurality of data writes to a null device,
• identifying, by the processor, a second plurality of data reads from the restarted application that occur after the predetermined checkpoint but before the first failure of the application, where the second plurality of data reads have been undone after the first failure of the application,
• retrieving, by the processor, data from the at least one data set in response to the second plurality of data reads,
• returning, by the processor, the data from the at least one data set to the restarted application, in response to the second plurality of data reads,
• identifying, by the processor, a second plurality of data writes from the restarted application, where the second plurality of data writes are associated with the data from the at least one data set, and
• writing, by the processor, the second plurality of data writes to the at least one data set.

A system, comprising:

• a processor;
• and
• logic integrated with the processor, executable by the processor, or integrated with and executable by the processor, the logic being configured to:
• establish a predetermined checkpoint and storing a log of duplicate read data in association with the predetermined checkpoint during a running of an application that is processing at least one data set, the duplicate read data including an image of all data retrieved from the at least one data set in response to a plurality of data reads made by the application before the predetermined checkpoint;
• identify a first failure of the application;
• and
• restart the application and performing a first replay of the application in response to the first failure, including:
• identify a first plurality of data reads from the restarted application that occur before the predetermined checkpoint,
• return the duplicate read data to the restarted application, in response to the first plurality of data reads,
• identify a first plurality of data writes from the application, where the first plurality of data writes include writes made by the application before the predetermined checkpoint,
• discard the first plurality of data writes by writing the first plurality of data writes to a null device,
• identify a second plurality of data reads from the restarted application that occur after the predetermined checkpoint but before the first failure of the application, where the second plurality of data reads have been undone after the first failure of the application,
• retrieve data from the at least one data set in response to the second plurality of data reads,
• return the data from the at least one data set to the restarted application, in response to the second plurality of data reads,
• identify a second plurality of data writes from the restarted application, where the second plurality of data writes are associated with the data from the at least one data set, and
• write the second plurality of data writes to the at least one data set.