Join

class tensorplay.distributed.algorithms.Join(joinables: list[Joinable], enable: bool = True, throw_on_early_termination: bool = False, **kwargs)[source]

This class defines the generic join context manager, which allows custom hooks to be called after a process joins.

These hooks should shadow the collective communications of non-joined processes to prevent hanging and erroring and to ensure algorithmic correctness. Refer to JoinHook for details about the hook definition.

Warning

The context manager requires each participating Joinable to call the method notify_join_context() before its own per- iteration collective communications to ensure correctness.

Parameters:

• joinables (List[Joinable]) – a list of the participating Joinable s; their hooks are iterated over in the given order.

• enable (bool) – a flag enabling uneven input detection; setting to False disables the context manager’s functionality and should only be set when the user knows the inputs will not be uneven (default: True).

• throw_on_early_termination (bool) – a flag controlling whether to throw an exception upon detecting uneven inputs (default: False).

static notify_join_context(joinable: Joinable)[source]

Notifies the join context manager that the calling process has not yet joined.

Then, if throw_on_early_termination=True, checks if uneven inputs have been detected (i.e. if one process has already joined) and throws an exception if so.

This method should be called from a Joinable object before its per-iteration collective communications. For example, this should be called at the beginning of the forward pass in DistributedDataParallel.

Only the first Joinable object passed into the context manager performs the collective communications in this method, and for the others, this method is vacuous.

Parameters:

joinable (Joinable) – the Joinable object calling this method.

Returns:

An async work handle for the all-reduce meant to notify the context manager that the process has not yet joined if joinable is the first one passed into the context manager; None otherwise.