Trace read requests (#2762)

test_runner/performance/test_read_trace.py

@@ -0,0 +1,31 @@
+from contextlib import closing
+
+from fixtures.neon_fixtures import NeonEnvBuilder
+
+
+# This test demonstrates how to collect a read trace. It's useful until
+# it gets replaced by a test that actually does stuff with the trace.
+def test_read_request_tracing(neon_env_builder: NeonEnvBuilder):
+    neon_env_builder.num_safekeepers = 1
+    env = neon_env_builder.init_start()
+
+    tenant, _ = env.neon_cli.create_tenant(
+        conf={
+            "trace_read_requests": "true",
+        }
+    )
+
+    timeline = env.neon_cli.create_timeline("test_trace_replay", tenant_id=tenant)
+    pg = env.postgres.create_start("test_trace_replay", "main", tenant)
+
+    with closing(pg.connect()) as conn:
+        with conn.cursor() as cur:
+            cur.execute("create table t (i integer);")
+            cur.execute(f"insert into t values (generate_series(1,{10000}));")
+            cur.execute("select count(*) from t;")
+
+    # Stop pg so we drop the connection and flush the traces
+    pg.stop()
+
+    trace_path = env.repo_dir / "traces" / str(tenant) / str(timeline)
+    assert trace_path.exists()