Reliable high-speed duplex printing mode configured to issue simplex-printing requests for individual sides based on a plurality of input duplex-printing requests for individual sheets

A non-transitory computer-readable recording medium having an image formation program recorded thereon, the program causing a computer to function as an image forming apparatus, the program causing the computer to function as:

• a high-speed duplex-printing mode execution unit configured to execute, if duplex image formation is to be performed, a high-speed duplex-printing mode in which (i) image formation is sequentially performed on first sides of a plurality of sheets starting from a leading sheet in a circulation direction in accordance with the number of sheets capable of being simultaneously circulated and (ii) image formation is subsequently performed on a second side of at least the leading sheet;
• a print request unit configured to issue simplex-printing requests for individual sides based on a plurality of input duplex-printing requests for individual sheets;
• an output processing unit configured to receive the simplex-printing requests for the individual sides, perform an output process, and cause image formation to be performed on corresponding sides;
• a request control unit configured to cause, in response to issuance of the plurality of duplex-printing requests, the print request unit to sequentially issue simplex-printing requests using, as a trigger, either input of each duplex-printing request or completion of the output process for a simplex-printing request in the output processing unit;
• and
• a request invalidation unit configured to maintain a trigger based on the completion of the output process invalidated until the number of duplex-printing requests that have been input becomes equal to the number of sheets for which sequential image formation on first sides is allowed.