[Perf] Evaluate API: Using threads to infer signatures for eval batch…

… runs instead of processes. (#3412)

# Description

This change is related to
#3380

# All Promptflow Contribution checklist:
- [ ] **The pull request does not introduce [breaking changes].**
- [ ] **CHANGELOG is updated for new features, bug fixes or other
significant changes.**
- [ ] **I have read the [contribution guidelines](../CONTRIBUTING.md).**
- [ ] **Create an issue and link to the pull request to get dedicated
review from promptflow team. Learn more: [suggested
workflow](../CONTRIBUTING.md#suggested-workflow).**

## General Guidelines and Best Practices
- [ ] Title of the pull request is clear and informative.
- [ ] There are a small number of commits, each of which have an
informative message. This means that previously merged commits do not
appear in the history of the PR. For more information on cleaning up the
commits in your PR, [see this
page](https://github.com/Azure/azure-powershell/blob/master/documentation/development-docs/cleaning-up-commits.md).

### Testing Guidelines
- [ ] Pull request includes test coverage for the included changes.

---------

Co-authored-by: Clement Wang <47586720+wangchao1230@users.noreply.github.com>

src/promptflow-devkit/promptflow/_proxy/_python_inspector_proxy.py

@@ -1,10 +1,11 @@
+import os
 import re
 from pathlib import Path
 from typing import Any, Dict, List
 
 from promptflow._constants import FlowEntryRegex
 from promptflow._core.entry_meta_generator import _generate_flow_meta
-from promptflow._sdk._constants import FLOW_META_JSON_GEN_TIMEOUT
+from promptflow._sdk._constants import FLOW_META_JSON_GEN_TIMEOUT, PF_FLOW_META_LOAD_IN_SUBPROCESS
 from promptflow._utils.flow_utils import resolve_python_entry_file
 
 from ._base_inspector_proxy import AbstractInspectorProxy
@@ -35,7 +36,7 @@ def get_entry_meta(
         **kwargs,
     ) -> Dict[str, Any]:
         timeout = kwargs.get("timeout", FLOW_META_JSON_GEN_TIMEOUT)
-        load_in_subprocess = kwargs.get("load_in_subprocess", True)
+        load_in_subprocess = os.environ.get(PF_FLOW_META_LOAD_IN_SUBPROCESS, "True").lower() == "true"
 
         flow_dag = {"entry": entry}
         # generate flow.json only for eager flow for now

src/promptflow-devkit/promptflow/_sdk/_constants.py

@@ -99,6 +99,7 @@ def _prepare_home_dir() -> Path:
 PF_SERVICE_DEBUG = "PF_SERVICE_DEBUG"
 PF_SYSTEM_METRICS_PREFIX = "__pf__"
 PF_FLOW_ENTRY_IN_TMP = "PF_FLOW_ENTRY_IN_TMP"
+PF_FLOW_META_LOAD_IN_SUBPROCESS = "PF_FLOW_META_LOAD_IN_SUBPROCESS"
 
 LOCAL_MGMT_DB_PATH = (HOME_PROMPT_FLOW_DIR / "pf.sqlite").resolve()
 LOCAL_MGMT_DB_SESSION_ACQUIRE_LOCK_PATH = (HOME_PROMPT_FLOW_DIR / "pf.sqlite.lock").resolve()

src/promptflow-evals/promptflow/evals/evaluate/_batch_run_client/batch_run_context.py

@@ -3,7 +3,7 @@
 # ---------------------------------------------------------
 import os
 
-from promptflow._sdk._constants import PF_FLOW_ENTRY_IN_TMP
+from promptflow._sdk._constants import PF_FLOW_ENTRY_IN_TMP, PF_FLOW_META_LOAD_IN_SUBPROCESS
 from promptflow._utils.user_agent_utils import ClientUserAgentUtil
 from promptflow.tracing._integrations._openai_injector import inject_openai_api, recover_openai_api
 
@@ -23,10 +23,12 @@ def __enter__(self):
 
         if isinstance(self.client, ProxyClient):
             os.environ[PF_FLOW_ENTRY_IN_TMP] = "true"
+            os.environ[PF_FLOW_META_LOAD_IN_SUBPROCESS] = "false"
 
     def __exit__(self, exc_type, exc_val, exc_tb):
         if isinstance(self.client, CodeClient):
             recover_openai_api()
 
         if isinstance(self.client, ProxyClient):
             os.environ.pop(PF_FLOW_ENTRY_IN_TMP, None)
+            os.environ.pop(PF_FLOW_META_LOAD_IN_SUBPROCESS, None)