chore: lazy load some imports

datadog_lambda/tracing.py

@@ -2,7 +2,6 @@
 # under the Apache License Version 2.0.
 # This product includes software developed at Datadog (https://www.datadoghq.com/).
 # Copyright 2019 Datadog, Inc.
-import hashlib
 import logging
 import os
 import base64
@@ -387,6 +386,8 @@ def extract_context_from_kinesis_event(event, lambda_context):
 
 
 def _deterministic_sha256_hash(s: str, part: str) -> int:
+    import hashlib
+
     sha256_hash = hashlib.sha256(s.encode()).hexdigest()
     # First two chars is '0b'. zfill to ensure 256 bits, but we only care about the first 128 bits
     binary_hash = bin(int(sha256_hash, 16))[2:].zfill(256)

datadog_lambda/wrapper.py

@@ -23,11 +23,6 @@
     XraySubsegment,
     Headers,
 )
-from datadog_lambda.metric import (
-    flush_stats,
-    submit_invocations_metric,
-    submit_errors_metric,
-)
 from datadog_lambda.module_name import modify_module_name
 from datadog_lambda.patch import patch_all
 from datadog_lambda.span_pointers import calculate_span_pointers
@@ -248,7 +243,11 @@ def __call__(self, event, context, **kwargs):
             self.response = self.func(event, context, **kwargs)
             return self.response
         except Exception:
-            submit_errors_metric(context)
+            if not should_use_extension:
+                from datadog_lambda.metric import submit_errors_metric
+
+                submit_errors_metric(context)
+
             if self.span:
                 self.span.set_traceback()
             raise
@@ -284,7 +283,12 @@ def _before(self, event, context):
         try:
             self.response = None
             set_cold_start(init_timestamp_ns)
-            submit_invocations_metric(context)
+
+            if not should_use_extension:
+                from datadog_lambda.metric import submit_invocations_metric
+
+                submit_invocations_metric(context)
+
             self.trigger_tags = extract_trigger_tags(event, context)
             # Extract Datadog trace context and source from incoming requests
             dd_context, trace_context_source, event_source = extract_dd_trace_context(
@@ -383,6 +387,8 @@ def _after(self, event, context):
                     logger.debug("Failed to create cold start spans. %s", e)
 
             if not self.flush_to_log or should_use_extension:
+                from datadog_lambda.metric import flush_stats
+
                 flush_stats(context)
             if should_use_extension and self.local_testing_mode:
                 # when testing locally, the extension does not know when an