Init

.gitignore

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+# Byte-compiled / optimized / DLL files
+__pycache__/
+*.py[cod]
+*$py.class
+
+# C extensions
+*.so
+
+# Distribution / packaging
+.Python
+build/
+develop-eggs/
+dist/
+downloads/
+eggs/
+.eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+wheels/
+share/python-wheels/
+*.egg-info/
+.installed.cfg
+*.egg
+MANIFEST
+
+# PyInstaller
+#  Usually these files are written by a python script from a template
+#  before PyInstaller builds the exe, so as to inject date/other infos into it.
+*.manifest
+*.spec
+
+# Installer logs
+pip-log.txt
+pip-delete-this-directory.txt
+
+# Unit test / coverage reports
+htmlcov/
+.tox/
+.nox/
+.coverage
+.coverage.*
+.cache
+nosetests.xml
+coverage.xml
+*.cover
+*.py,cover
+.hypothesis/
+.pytest_cache/
+cover/
+
+# Translations
+*.mo
+*.pot
+
+# Django stuff:
+*.log
+local_settings.py
+db.sqlite3
+db.sqlite3-journal
+
+# Flask stuff:
+instance/
+.webassets-cache
+
+# Scrapy stuff:
+.scrapy
+
+# Sphinx documentation
+docs/_build/
+
+# PyBuilder
+.pybuilder/
+target/
+
+# Jupyter Notebook
+.ipynb_checkpoints
+
+# IPython
+profile_default/
+ipython_config.py
+
+# pyenv
+#   For a library or package, you might want to ignore these files since the code is
+#   intended to run in multiple environments; otherwise, check them in:
+# .python-version
+
+# pipenv
+#   According to pypa/pipenv#598, it is recommended to include Pipfile.lock in version control.
+#   However, in case of collaboration, if having platform-specific dependencies or dependencies
+#   having no cross-platform support, pipenv may install dependencies that don't work, or not
+#   install all needed dependencies.
+#Pipfile.lock
+
+# poetry
+#   Similar to Pipfile.lock, it is generally recommended to include poetry.lock in version control.
+#   This is especially recommended for binary packages to ensure reproducibility, and is more
+#   commonly ignored for libraries.
+#   https://python-poetry.org/docs/basic-usage/#commit-your-poetrylock-file-to-version-control
+#poetry.lock
+
+# pdm
+#   Similar to Pipfile.lock, it is generally recommended to include pdm.lock in version control.
+#pdm.lock
+#   pdm stores project-wide configurations in .pdm.toml, but it is recommended to not include it
+#   in version control.
+#   https://pdm.fming.dev/#use-with-ide
+.pdm.toml
+
+# PEP 582; used by e.g. github.com/David-OConnor/pyflow and github.com/pdm-project/pdm
+__pypackages__/
+
+# Celery stuff
+celerybeat-schedule
+celerybeat.pid
+
+# SageMath parsed files
+*.sage.py
+
+# Environments
+.env
+.venv
+env/
+venv/
+ENV/
+env.bak/
+venv.bak/
+
+# Spyder project settings
+.spyderproject
+.spyproject
+
+# Rope project settings
+.ropeproject
+
+# mkdocs documentation
+/site
+
+# mypy
+.mypy_cache/
+.dmypy.json
+dmypy.json
+
+# Pyre type checker
+.pyre/
+
+# pytype static type analyzer
+.pytype/
+
+# Cython debug symbols
+cython_debug/
+
+# PyCharm
+#  JetBrains specific template is maintained in a separate JetBrains.gitignore that can
+#  be found at https://github.com/github/gitignore/blob/main/Global/JetBrains.gitignore
+#  and can be added to the global gitignore or merged into this file.  For a more nuclear
+#  option (not recommended) you can uncomment the following to ignore the entire idea folder.
+.idea/

README.md

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+# karton memory watcher
+
+Working for several months in a row, tasks gradually become more and more significant in terms of RAM consumption.
+And sometimes forcing a call to the garbage collector doesn't help.
+This is especially felt when working with libraries that help to parse certain file formats -
+at the start, the process takes up 60 megabytes of RAM, and after a couple of months - 400.
+
+This library is a watcher that monitors the gradual increase in the service's RAM usage and shuts
+it upon reaching a set threshold.
+
+### For what ways to run karton consumer is it suitable?
+
+For every way that uses autorestart. For example, I can suggest at least three of them:
+
+1. systemctl service restart policy: `on-failure` / `always`
+2. docker service restart policy: `on-failure` / `always` / `unless-stopped`
+3. Screen infinite loop: `while true; do your_app; sleep 10; done`
+
+
+### How to use it
+
+Simple way:
+```python
+from karton.core import Consumer
+from karton.memory_watcher import implant_watcher, RestartBehavior, RestartRule
+
+...
+class YourConsumer(Consumer):
+    pass
+
+if __name__ == "__main__":
+    foobar = YourConsumer()
+    implant_watcher(
+        foobar,
+        RestartRule(
+            extra_consumed_memory_percent=80,
+            # call_before_exit=(close_db_connections, )
+        )
+    )
+    foobar.loop()
+
+```
+
+RestartRule modes:
+1. `proceed_tasks`: count of tasks to proceed for restart
+2. `elapsed_time`: how many seconds should pass
+3. `extra_consumed_memory_percent`: extra memory used in % (100% means twice of memory compared to point before starting first task). It uses megabytes to calculate percents.
+4. `extra_consumed_megabytes`: extra memory used in megabytes (e.g. your service at start uses 60MB and you need to kill it if it consumes extra 500+ MB)
+
+You can see usage cases in [tests](./tests).
+
+### Alternatives?
+
+#### Systemctl:
+
+In January 2023 there is a nice feature request about MemoryMax policy:
+https://github.com/systemd/systemd/issues/25966
+
+Also writing your own agent that will track memory leaks and send systemctl service to restart (but be careful not to kill ongoing tasks!).
+
+#### Docker
+
+wip, feel free to suggest how to gently restart container to allow task normally proceed

karton/memory_watcher/__init__.py

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+from .watcher import (
+    MemoryWatcherExitException,
+    RestartBehavior,
+    RestartRule,
+    implant_watcher,
+)

karton/memory_watcher/watcher.py

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+import time
+from enum import Enum
+from typing import Callable
+
+import karton.core
+import psutil
+
+
+class RestartBehavior(Enum):
+    # We cannot exit by raising exception - there is an exception handler:
+    # https://github.com/CERT-Polska/karton/blob/2d10bd432928354a2030a0ee8aa976b64f4acb63/karton/core/karton.py#L301
+    # RAISE_EXCEPTION = -1
+    EXIT_0 = 1
+    EXIT_1 = 2
+
+
+class MemoryWatcherExitException(Exception):
+    pass
+
+
+class RestartRule:
+    def __init__(
+        self,
+        call_before_exit: tuple[Callable] = tuple(),
+        proceed_tasks: int = None,
+        elapsed_time: int = None,
+        extra_consumed_memory_percent: int = None,
+        extra_consumed_megabytes: int = None,
+        restart_behavior: RestartBehavior = RestartBehavior.EXIT_0,
+    ):
+        """
+        Body of restart routine
+        At least one of parameters should be set:
+
+        :param call_before_exit: one or more functions that need to call before exit
+        :param proceed_tasks: count of tasks to proceed for restart
+        :param elapsed_time: how many seconds should pass
+        :param extra_consumed_memory_percent: extra memory used in % (100% means twice of memory compared to point before starting first task)
+        :param extra_consumed_megabytes: extra memory used in megabytes (e.g. your service at start uses 60MB and you need to kill it if it consumes extra 500+ MB)
+
+        Need to mention that the rule will be
+        """
+        if all(
+            a is None
+            for a in (
+                proceed_tasks,
+                elapsed_time,
+                extra_consumed_memory_percent,
+                extra_consumed_megabytes,
+            )
+        ):
+            raise Exception("You should set at least one parameter!")
+
+        self.call_before_exit = call_before_exit
+
+        self.rule_proceed_tasks = proceed_tasks
+        self.rule_elapsed_time = elapsed_time
+        self.rule_extra_consumed_memory_percent = extra_consumed_memory_percent
+        self.rule_extra_consumed_megabytes = extra_consumed_megabytes
+
+        self.restart_behavior = restart_behavior
+
+        self.prehooked = False
+        self.tasks_counter = None
+        self.start_time = None
+        self.start_memory_usage = None
+
+    @staticmethod
+    def get_process_memory_usage():
+        return psutil.Process().memory_info().rss // 1024 // 1024
+
+    def pre_hook_behavior(self, *args, **kwargs):
+        """
+        Init starting variables
+        """
+        if not self.prehooked:
+            self.tasks_counter = 0
+            self.start_memory_usage = self.get_process_memory_usage()
+            self.start_time = time.time()
+            self.prehooked = True
+
+    def post_hook_behavior(self, *args, **kwargs):
+        """
+        Check that everything is okay, so we don't need to restart
+        """
+        self.tasks_counter += 1
+
+        # Trigger on count of proceed tasks (decrease call-based errors)
+        if self.rule_proceed_tasks is not None:
+            if self.tasks_counter >= self.rule_proceed_tasks:
+                self.execute_restart_behavior(
+                    f"rule_proceed_tasks: {self.tasks_counter} >= {self.rule_proceed_tasks}"
+                )
+
+        # Trigger on elapsed time (decrease time-based errors)
+        if self.rule_elapsed_time is not None:
+            current_time = time.time()
+            if current_time - self.start_time >= self.rule_elapsed_time:
+                self.execute_restart_behavior(
+                    f"rule_elapsed_time: {current_time} - {self.start_time} >= {self.rule_elapsed_time}"
+                )
+
+        # Trigger on memory usage
+        if (
+            self.rule_extra_consumed_megabytes is not None
+            or self.rule_extra_consumed_memory_percent is not None
+        ):
+            memory_usage = self.get_process_memory_usage()
+
+            if self.rule_extra_consumed_megabytes is not None:
+                if (
+                    memory_usage - self.start_memory_usage
+                    >= self.rule_extra_consumed_megabytes
+                ):
+                    self.execute_restart_behavior(
+                        f"rule_extra_consumed_megabytes: {memory_usage} - {self.start_memory_usage} >= {self.rule_extra_consumed_megabytes}"
+                    )
+
+            if self.rule_extra_consumed_memory_percent is not None:
+                if (
+                    memory_usage / self.start_memory_usage - 1
+                    >= self.rule_extra_consumed_memory_percent / 100
+                ):
+                    self.execute_restart_behavior(
+                        f"extra_consumed_memory_percent: {memory_usage} / {self.start_memory_usage} - 1 >= {self.rule_extra_consumed_memory_percent} / 100"
+                    )
+
+    def execute_restart_behavior(self, reason):
+        print(f"Restart policy triggered, reason: {reason}")
+
+        for call in self.call_before_exit:
+            call()
+
+        if self.restart_behavior == RestartBehavior.EXIT_0:
+            exit(0)
+
+        if self.restart_behavior == RestartBehavior.EXIT_1:
+            exit(1)
+
+
+def implant_watcher(consumer: karton.core.Consumer, rule: RestartRule):
+    consumer.add_pre_hook(rule.pre_hook_behavior, "Karton Memory Watcher pre-hook")
+    consumer.add_post_hook(rule.post_hook_behavior, "Karton Memory Watcher post-hook")
+    # just in case if someone will call `my_consumer = implant_watcher(my_consumer, ...)`
+    return consumer