Streaming Iterators

  • The GoogleAdsService.search_stream method returns a streaming response iterator.

  • The iterator should stay in the same scope as the GoogleAdsService client to prevent broken streams or segmentation faults.

  • If the GoogleAdsService object goes out of scope before the iterator is used, the underlying gRPC Channel object may be garbage-collected, leading to undefined behavior.

  • Accessing the iterator in a different scope than where the service object was created is incorrect usage.

  • The correct approach is to keep the streaming iterator in the same scope as the GoogleAdsService client while it is being used.

When calling GoogleAdsService.search_stream, a streaming response iterator is returned. This iterator should remain in the same scope as the GoogleAdsService client while being used in order to avoid broken streams or segmentation faults. This is because the gRPC Channel object is garbage-collected once the open GoogleAdsService object goes out of scope. If the GoogleAdsService object is no longer in scope by the time the iteration occurs on the result of search_stream, the Channel object may already be destroyed, causing undefined behavior when the iterator attempts to retrieve the next value.

The following code demonstrates incorrect usage of streaming iterators:

def stream_response(client, customer_id, query):
    return client.get_service("GoogleAdsService", version="v22").search_stream(customer_id, query=query)

def main(client, customer_id):
    query = "SELECT campaign.name FROM campaign LIMIT 10"
    response = stream_response(client, customer_id, query=query)
    # Access the iterator in a different scope from where the service object was created.
    try:
        for batch in response:
            # Iterate through response, expect undefined behavior.

In the above code, the GoogleAdsService object is created within a different scope from where the iterator is accessed. As a result, the Channel object may be destroyed before the iterator consumes the entire response.

Instead, the streaming iterator should remain in the same scope as the GoogleAdsService client for as long as it is being used:

def main(client, customer_id):
    ga_service = client.get_service("GoogleAdsService", version="v22")
    query = "SELECT campaign.name FROM campaign LIMIT 10"
    response = ga_service.search_stream(customer_id=customer_id, query=query)
    # Access the iterator in the same scope as where the service object was created.
    try:
        for batch in response:
            # Successfully iterate through response.