Using locks to prevent multiple rebuilds of the same source

A method comprises:

• determining, by a first rebuilding agent of a plurality of rebuilding agents of a dispersed storage network (DSN), to rebuild one or more encoded data slices of a plurality of sets of encoded data slices;
• when determined to rebuild the one or more encoded data slices, sending, by the first rebuilding agent, a lock request to a set of storage units of the DSN regarding the plurality of sets of encoded data slices;
• determining, by the first rebuilding agent, whether at least a decode threshold number of favorable lock responses is received from the set of storage units;
• when the at least the decode threshold number of favorable lock responses is received, recovering, by the first rebuilding agent, one or more sets of encoded data slices of the plurality of sets of encoded data slices to rebuild the one or more encoded data slices to produce one or more rebuilt encoded data slices;
• for a rebuilt encoded data slice of the one or more rebuilt encoded data slices, determining, by the first rebuilding agent, whether a storage unit of the set of storage units that is targeted to receive the rebuilt encoded data slice is available to store the rebuilt encoded data slice;
• and
• when the storage unit is available to store the rebuilt encoded data slice, sending, by the first rebuilding agent, the rebuilt encoded data slice to the storage unit.