fix: Reduce logging system overhead

dev/environment-dev.yml

@@ -29,6 +29,7 @@ dependencies:
   - mitmproxy
   - pytest >=7.3.0
   - pytest-asyncio
+  - pytest-timeout
   - pytest-xprocess
   - requests
   - sel(win): pywin32

libmamba/src/solver/libsolv/database.cpp

@@ -109,7 +109,19 @@ namespace mamba::solver::libsolv
 
     void Database::set_logger(logger_type callback)
     {
-        ::pool_setdebuglevel(pool().raw(), std::numeric_limits<int>::max());  // All
+        // We must not use more than the penultimate level of verbosity of libsolv (which is 3) to
+        // avoid the most verbose messages (of type SOLV_DEBUG_RULE_CREATION | SOLV_DEBUG_WATCHES),
+        // which might spam the output and make mamba hang. See:
+        // https://github.com/openSUSE/libsolv/blob/27aa6a72c7db73d78aa711ae412231768e77c9e0/src/pool.c#L1623-L1637
+        // TODO: Make `level` configurable once the semantics and UX for verbosity are clarified.
+        // Currently, we use the behavior of `1.x` whose default value for the verbosity level was
+        // `0` in which case the logs of libsolv were not transferred. See:
+        // https://github.com/mamba-org/mamba/blob/4f269258b4237a342da3e9891045cdd51debb27c/libmamba/include/mamba/core/context.hpp#L88
+        // See: https://github.com/mamba-org/mamba/blob/1.x/libmamba/src/core/pool.cpp#L72
+        // Instead use something like:
+        // const int level = Context().output_params.verbosity - 1;
+        const int level = 0;
+        ::pool_setdebuglevel(pool().raw(), level);
         pool().set_debug_callback(
             [logger = std::move(callback)](const solv::ObjPoolView&, int type, std::string_view msg) noexcept
             {

micromamba/tests/env-logging-overhead-regression.yaml

@@ -0,0 +1,17 @@
+# This environment was observed to have the spdlog-based logging system make
+# mamba hang when environments are created with:
+#
+#   {micromamba,mamba} env create -n repro-create -f ./env-logging-overhead-regression.yaml
+#
+# or updated with:
+#
+#   {micromamba,mamba} env update -n repro-create -f ./env-logging-overhead-regression.yaml
+#
+channels:
+  - conda-forge
+dependencies:
+  - python=3.9
+  - xeus-cling=0.6.0
+  - xtensor=0.20.8
+  - xtensor-blas=0.16.1
+  - notebook

micromamba/tests/test_create.py

@@ -143,6 +143,24 @@ def test_env_lockfile_different_install_after_create(tmp_home, tmp_root_prefix,
     helpers.install("-p", env_prefix, "-f", install_spec_file, "-y", "--json")
 
 
+# Only run this test on Linux, as it is the only platform where xeus-cling
+# (which is part of the environment) is available.
+@pytest.mark.timeout(20)
+@pytest.mark.skipif(platform.system() != "Linux", reason="Test only available on Linux")
+@pytest.mark.parametrize("shared_pkgs_dirs", [True], indirect=True)
+def test_env_logging_overhead_regression(tmp_home, tmp_root_prefix, tmp_path):
+    # Non-regression test https://github.com/mamba-org/mamba/issues/3415.
+
+    env_prefix = tmp_path / "myenv"
+    create_spec_file = tmp_path / "env-logging-overhead-regression.yaml"
+
+    shutil.copyfile(__this_dir__ / "env-logging-overhead-regression.yaml", create_spec_file)
+
+    # Must not hang
+    res = helpers.create("-p", env_prefix, "-f", create_spec_file, "-y", "--json", "--dry-run")
+    assert res["success"]
+
+
 @pytest.mark.parametrize("shared_pkgs_dirs", [True], indirect=True)
 @pytest.mark.parametrize("root_prefix_type", (None, "env_var", "cli"))
 @pytest.mark.parametrize("target_is_root", (False, True))

micromamba/tests/test_remove.py

@@ -47,10 +47,7 @@ def test_remove_orphaned(tmp_home, tmp_root_prefix, tmp_xtensor_env, tmp_env_nam
     assert keys.issubset(set(res.keys()))
     assert res["success"]
 
-    if sys.platform == "darwin" and platform.machine() == "arm64":
-        assert len(res["actions"]["UNLINK"]) == 12
-    else:
-        assert len(res["actions"]["UNLINK"]) == 11
+    assert len(res["actions"]["UNLINK"]) == 12
     assert res["actions"]["UNLINK"][0]["name"] == "xtensor-python"
     assert res["actions"]["PREFIX"] == str(tmp_xtensor_env)
 
@@ -64,7 +61,7 @@ def test_remove_orphaned(tmp_home, tmp_root_prefix, tmp_xtensor_env, tmp_env_nam
     # assert len(res["actions"]["UNLINK"]) == len(env_pkgs) + (
     assert len(res["actions"]["UNLINK"]) == 3 + (
         1 if helpers.dry_run_tests == helpers.DryRun.DRY else 0
-    )
+    ) + (platform.system() == "Linux")  # xtl is not removed on Linux
     for p in res["actions"]["UNLINK"]:
         assert p["name"] in env_pkgs
     assert res["actions"]["PREFIX"] == str(tmp_xtensor_env)