perf(hogql): Fix C++ parser leaks (#18022)

hogql_parser/setup.py

@@ -32,7 +32,7 @@
 
 setup(
     name="hogql_parser",
-    version="0.1.7",
+    version="0.1.8",
     url="https://github.com/PostHog/posthog/tree/master/hogql_parser",
     author="PostHog Inc.",
     author_email="[email protected]",

posthog/hogql/test/_test_parser.py

@@ -6,11 +6,18 @@
 from posthog.hogql.errors import HogQLException, SyntaxException
 from posthog.hogql.parser import parse_expr, parse_order_expr, parse_select
 from posthog.hogql.visitor import clear_locations
-from posthog.test.base import BaseTest
+from posthog.test.base import BaseTest, MemoryLeakTestMixin
 
 
 def parser_test_factory(backend: Literal["python", "cpp"]):
-    class TestParser(BaseTest):
+    base_classes = (MemoryLeakTestMixin, BaseTest) if backend == "cpp" else (BaseTest,)
+
+    class TestParser(*base_classes):
+        MEMORY_INCREASE_PER_PARSE_LIMIT_B = 10_000
+        MEMORY_INCREASE_INCREMENTAL_FACTOR_LIMIT = 0.1
+        MEMORY_PRIMING_RUNS_N = 2
+        MEMORY_LEAK_CHECK_RUNS_N = 100
+
         maxDiff = None
 
         def _expr(self, expr: str, placeholders: Optional[Dict[str, ast.Expr]] = None) -> ast.Expr:

posthog/test/base.py

@@ -1,6 +1,7 @@
 import datetime as dt
 import inspect
 import re
+import resource
 import threading
 import uuid
 from contextlib import contextmanager
@@ -194,6 +195,41 @@ def validate_basic_html(self, html_message, site_url, preheader=None):
             self.assertIn(preheader, html_message)  # type: ignore
 
 
+class MemoryLeakTestMixin:
+    MEMORY_INCREASE_PER_PARSE_LIMIT_B: int
+    """Parsing more than once can never increase memory by this much (on average)"""
+    MEMORY_INCREASE_INCREMENTAL_FACTOR_LIMIT: float
+    """Parsing cannot increase memory by more than this factor * priming's increase (on average)"""
+    MEMORY_PRIMING_RUNS_N: int
+    """How many times to run every test method to prime the heap"""
+    MEMORY_LEAK_CHECK_RUNS_N: int
+    """How many times to run every test method to check for memory leaks"""
+
+    def _callTestMethod(self, method):
+        mem_original_b = resource.getrusage(resource.RUSAGE_SELF).ru_maxrss
+        for _ in range(self.MEMORY_PRIMING_RUNS_N):  # Priming runs
+            method()
+        mem_primed_b = resource.getrusage(resource.RUSAGE_SELF).ru_maxrss
+        for _ in range(self.MEMORY_LEAK_CHECK_RUNS_N):  # Memory leak check runs
+            method()
+        mem_tested_b = resource.getrusage(resource.RUSAGE_SELF).ru_maxrss
+        avg_memory_priming_increase_b = (mem_primed_b - mem_original_b) / self.MEMORY_PRIMING_RUNS_N
+        avg_memory_test_increase_b = (mem_tested_b - mem_primed_b) / self.MEMORY_LEAK_CHECK_RUNS_N
+        avg_memory_increase_factor = (
+            avg_memory_test_increase_b / avg_memory_priming_increase_b if avg_memory_priming_increase_b else 0
+        )
+        self.assertLessEqual(  # type: ignore
+            avg_memory_test_increase_b,
+            self.MEMORY_INCREASE_PER_PARSE_LIMIT_B,
+            f"Possible memory leak - exceeded {self.MEMORY_INCREASE_PER_PARSE_LIMIT_B}-byte limit of incremental memory per parse",
+        )
+        self.assertLessEqual(  # type: ignore
+            avg_memory_increase_factor,
+            self.MEMORY_INCREASE_INCREMENTAL_FACTOR_LIMIT,
+            f"Possible memory leak - exceeded {self.MEMORY_INCREASE_INCREMENTAL_FACTOR_LIMIT*100:.2f}% limit of incremental memory per parse",
+        )
+
+
 class BaseTest(TestMixin, ErrorResponsesMixin, TestCase):
     """
     Base class for performing Postgres-based backend unit tests on.

requirements.in

@@ -87,4 +87,4 @@ django-two-factor-auth==1.14.0
 phonenumberslite==8.13.6
 openai==0.27.8
 nh3==0.2.14
-hogql-parser==0.1.7
+hogql-parser==0.1.8

requirements.txt

@@ -248,7 +248,7 @@ gunicorn==20.1.0
     # via -r requirements.in
 h11==0.13.0
     # via wsproto
-hogql-parser==0.1.7
+hogql-parser==0.1.8
     # via -r requirements.in
 idna==2.8
     # via