cupy.cuda.Stream

class cupy.cuda.Stream(null=False, non_blocking=False, ptds=False)

CUDA stream.

This class handles the CUDA stream handle in RAII way, i.e., when an Stream instance is destroyed by the GC, its handle is also destroyed.

Note that if both null and ptds are False, a plain new stream is created.

Parameters
  • null (bool) – If True, the stream is a null stream (i.e. the default stream that synchronizes with all streams). Note that you can also use the Stream.null singleton object instead of creating a new null stream object.

  • ptds (bool) – If True and null is False, the per-thread default stream is used. Note that you can also use the Stream.ptds singleton object instead of creating a new per-thread default stream object.

  • non_blocking (bool) – If True and both null and ptds are False, the stream does not synchronize with the NULL stream.

Variables
  • ptr (intptr_t) – Raw stream handle.

  • device_id (int) – The ID of the device that the stream was created on. The value -1 is used for the singleton stream objects.

Methods

__enter__(self)
__exit__(self, *args)
add_callback(self, callback, arg)

Adds a callback that is called when all queued work is done.

Parameters
  • callback (function) – Callback function. It must take three arguments (Stream object, int error status, and user data object), and returns nothing.

  • arg (object) – Argument to the callback.

Note

Whenever possible, use the launch_host_func() method instead of this one, as it may be deprecated and removed from CUDA at some point.

launch_host_func(self, callback, arg)

Launch a callback on host when all queued work is done.

Parameters
  • callback (function) – Callback function. It must take only one argument (user data object), and returns nothing.

  • arg (object) – Argument to the callback.

Note

Whenever possible, this method is recommended over add_callback(), which may be deprecated and removed from CUDA at some point.

record(self, event=None)

Records an event on the stream.

Parameters

event (None or cupy.cuda.Event) – CUDA event. If None, then a new plain event is created and used.

Returns

The recorded event.

Return type

cupy.cuda.Event

synchronize(self)

Waits for the stream completing all queued work.

use(self)

Makes this stream current.

If you want to switch a stream temporarily, use the with statement.

wait_event(self, event)

Makes the stream wait for an event.

The future work on this stream will be done after the event.

Parameters

event (cupy.cuda.Event) – CUDA event.

__eq__(self, other)
__ne__(value, /)

Return self!=value.

__lt__(value, /)

Return self<value.

__le__(value, /)

Return self<=value.

__gt__(value, /)

Return self>value.

__ge__(value, /)

Return self>=value.

Attributes

done

True if all work on this stream has been done.

null = <Stream 0 (device -1)>
ptds = <Stream 2 (device -1)>