solprop.backends.host.group_session#

The NumPy reference’s group session (SEP 47 section 6.7).

HostGroupSession is the GroupSession that serves every numpy_ref group, in both precisions, and HostPreparedGroup is the prepared group a reference backend returns from prepare_group. The group loads each member from its start and hands the loaded members to the reference’s group runner (HostGroup, or its member-axis arithmetic NumpyBatchBackend in binary64, the choice the reference’s registry row makes through solprop.backends.registry.select_batch()), which advances every member through each step of the common fixed schedule in turn. The session presents that march through the group protocol: one window per save plane, each member’s own events, tickets, counters and outcome, and the failure distinction of SEP 47 section 6.7.

Why the runner, rather than one HostSession per member. The native group composes one native session per member (solprop_native.group.NativeGroupSession), each advancing a whole window before the next. The reference group keeps its runner because what it must preserve is the runner’s, and composed member sessions would change all three:

Its arithmetic. A binary64 group evaluates its stages on arrays with a leading member axis (NumpyBatchBackend), whose reductions are ordered differently from a lone run’s: a member and its lone run agree to rounding, not bitwise (tests/backends/test_batch_lockstep.py). Member sessions would run the lone path and change every binary64 group’s result.
Its failure positions. Members take each common step in turn, so a failure in one member ends the group with the members ahead of it in flight at that step’s end (poisoned) and those behind it at the step’s start (SEP 47 section 6.7). Member sessions advancing whole windows in turn would leave the members ahead committed at the window’s end instead.
Its precision rule. The runner refuses a group of mixed precisions and runs single-precision members each on its own binary32 trial (HostGroup, lockstep_runner).

Each member’s boundary monitor is still its own: a stop ends that member alone while the others go on (member_stops).

Classes

`HostGroupSession`(members, problems, ...[, stop])	The reference's `GroupSession`.
`HostPreparedGroup`(members, problems, requests)	A prepared group of reference members (SEP 47 section 6.7).

class solprop.backends.host.group_session.HostGroupSession(members, problems, requests, starts, *, stop=None)[source]#

Bases: object

The reference’s GroupSession.

As the batched scan always has, the first advance gives every member its boundary monitor before the launch plane is reported, so that a launch a monitor refuses ends that member at once.

Parameters:

memberscollections.abc.Sequence of solprop.backends.protocol.Backend: One constructed reference backend per member, all of one backend. Once the group is constructed it owns them and closes them with itself; a construction that fails leaves them to the caller.
problemscollections.abc.Sequence of solprop.translate.problem.PropagationProblem: Each member’s independently translated problem.
requestscollections.abc.Sequence of solprop.translate.run_request.RunRequest: Each member’s run request, with its own fresh boundary monitor; their save planes and statistics are the group’s common schedule.
startscollections.abc.Sequence of solprop.backends.session.Start: Each member’s start: its entrance, with no method history or monitor to continue. The group takes each start’s field.
stopsolprop.log.StopFlag or None, optional: A group-wide stop token, polled before every common step.

Raises:

solprop.backends.session.SessionError: If the sequences differ in length or are empty, or if a start is not a fresh entrance.
solprop.exceptions.BackendError: If the runner refuses the members (select_batch): another backend, or another schedule, planes, precision or periodic statistics.

acknowledge(receipt)[source]#

Release the pending batch and allow advancing past it.

Parameters:

receiptsolprop.backends.events.Receipt: The pending batch’s receipt.

advance()[source]#

Run every running member through the next common window, and report it.

Returns:

solprop.backends.events.GroupBatch: Each member’s events in the window.

close()[source]#

Release every member and the runner; idempotent.

property closed: bool[source]#

Return whether the group was closed.

Returns:

bool: True once closed.

execution_record(member)[source]#

Return one member’s execution facts, with the group’s strategy.

Parameters:

memberint: The member’s position.

Returns:

collections.abc.Mapping: Its backend provenance.

export(member, ticket, recipe, out=None)[source]#

Fill a destination with one member’s converted field at a pending ticket.

Parameters:

memberint: The member’s position.
ticketsolprop.backends.events.ExportTicket: A ticket of the pending batch, for this member: its position is the member’s own.
recipesolprop.backends.export.ExportRecipe: The conversion.
outnumpy.ndarray or None, optional: The destination; a new array by default.

Returns:

numpy.ndarray: The member’s converted field.

property finished: bool[source]#

Return whether the group’s terminal batch was issued.

Returns:

bool: True once every member has ended.

member_status(member)[source]#

Return one member’s committed position, counters and outcome.

Parameters:

memberint: The member’s position.

Returns:

solprop.backends.session.SessionStatus: Its status; a member that ended reports its own outcome while the group goes on.

monitor_record(member)[source]#

Return one member’s boundary-monitor record.

Parameters:

memberint: The member’s position.

Returns:

collections.abc.Mapping or None: Its record as it closed or as it stands, or None when unwatched.

property n_members: int[source]#

Return the number of members.

Returns:

int: The members.

noise_phase(member, ticket)[source]#

Return one member’s noise phase at a pending ticket.

Parameters:

memberint: The member’s position.
ticketsolprop.backends.events.ExportTicket: A ticket of the pending batch.

Returns:

numpy.ndarray or None: The phase, shape (n_modes, n_pol, n_omega), or None without noise.

class solprop.backends.host.group_session.HostPreparedGroup(members, problems, requests)[source]#

Bases: object

A prepared group of reference members (SEP 47 section 6.7).

Each start() opens one HostGroupSession over the members.

Parameters:

memberscollections.abc.Sequence of solprop.backends.protocol.Backend: One constructed reference backend per member, all of one backend; they stay the caller’s until a started group owns them.
problemscollections.abc.Sequence of solprop.translate.problem.PropagationProblem: Each member’s independently translated problem.
requestscollections.abc.Sequence of solprop.translate.run_request.RunRequest: Each member’s run request.

property backend: str[source]#

Return the registered name of the backend that prepared it.

Returns:

str: The first member’s registered name.

start(starts, *, stop=None)[source]#

Start the group over the reference’s group runner.

Parameters:

startscollections.abc.Sequence of solprop.backends.session.Start: Each member’s entrance; the group takes their fields.
stopsolprop.log.StopFlag or None, optional: A group-wide stop token.

Returns:

HostGroupSession: The started group.