Context Management

aclError aclrtCreateContext(aclrtContext *context, int32_t deviceId)

context, ret = acl.rt.create_context(device_id)

Explicitly creates a context, which contains two streams, one default stream, and one stream for internal synchronization. It is a synchronous interface.

The following application scenarios are supported:

• If the acl.rt.create_context interface is not called to display the created context, the system uses the default context, which is created implicitly when acl.rt.set_device is called.
  • Implicitly created context: It is applicable to simple applications without complex interaction logic. However, in multi-thread programming, the execution result depends on the thread scheduling sequence.
  • (Recommended) Explicitly created context: It is applicable to large-scale applications with complex interaction logic, improving application readability and maintainability.
• If multiple contexts are created in a process, the current thread can use only one context at a time. It is recommended that acl.rt.set_current_context be used to specify the context of the current thread to improve program maintainability. (The number of contexts depends on the number of streams.)

device_id: int, ID of the device for which the context is to be created.

context: int, pointer to the created context in C.

ret: int, error code.

• 0 indicates success.
• Other values indicate failure.

None

None

aclError aclrtDestroyContext(aclrtContext context)

ret = acl.rt.destroy_context(context)

Destroys a context and releases the resources of the context. It is a synchronous interface. Only the context created by calling acl.rt.create_context can be destroyed.

Context: int, context object pointer to be destroyed. The context object can be obtained using create or get.

ret: int, error code.

• 0 indicates success.
• Other values indicate failure.

Do not destroy the context repeatedly. Otherwise, a segment error occurs.

Destruction API: The released or destroyed resources are no longer available after this API is called. You are advised to set the released or destroyed resources to invalid values (for example, 0 or None) after calling this API.

None

aclError aclrtSetCurrentContext(aclrtContext context)

ret = acl.rt.set_context(context)

Sets context of a thread. It is a synchronous interface.

context: int, current context object pointer of the thread.

ret: int, error code.

• 0 indicates success.
• Other values indicate failure.

• If the device corresponding to the context set for the thread has been reset, the context cannot be set as the thread context. Otherwise, exceptions may occur.
• It is recommended that the context created in a thread be used in the thread. If thread A calls acl.rt.create_context to create a context and thread B uses this context, you need to ensure the tasks execution sequence of the two threads that are in the same stream of the same context.

The validity of the input parameters of this API must be ensured by users.

aclError aclrtGetCurrentContext(aclrtContext *context)

Context, ret = acl.rt.get_context()

Obtains the context of a thread. It is a synchronous interface.

None

context: int, context object pointer.

ret: int, error code.

• 0 indicates success.
• Other values indicate failure.

None

None