Thread suspension system and method using trapping instructions

A computer program product encoded in computer readable media, the computer program product comprising:

• an instruction sequence including an operation that coincides with a safe point therein, wherein the operation is encoded in an otherwise unused position in the instruction sequence and is executable at least partially in parallel with one or more operations of the instruction sequence,
• the operation referencing a state that selectively triggers suspension of the instruction sequence at the safe point.

A computer-implemented method of providing mutator code with support for suspension of at least one execution thread thereof at a safe point, the method comprising:

• encoding information accessible to a collector process to identify at least a portion of a root set of storage locations at a safe point in the execution sequence of instructions;
• and
• encoding in an otherwise unused operation position of an instruction instance that coincides with the safe point, a conditional trap operation that references storage encodable with an exception triggering value to trigger an exception for suspending execution of the mutator code at the safe point.

A computer program product comprising:

• a compiler that generates an execution sequence of instructions including an explicit encoding of parallelism amongst component operations thereof, and which encodes in an otherwise unused component operation position an operation instance that references storage encodable with an exception triggering value to trigger an exception when the operation instance is executed as part of a mutator and to thereby suspend execution of the mutator at a safe point;
• and
• a map generator that supplies a collector process with information identifying a root set of storage locations in use by the mutator for pointer storage at the safe point, the safe point coinciding with the operation instance.

A method of advancing plural threads to coordination points in respective execution paths thereof, the method comprising:

• encoding an exception triggering value in storage referenced by respective instances of one or more operations encoded in respective otherwise unused operation positions in each of the plural threads;
• for each of the plural threads, suspending execution thereof in response to execution of a respective operation instance, the respective operation instance coinciding with one of the coordination points therein.