python - 为了避免内存泄漏，我应该在我的 python 云函数中避免哪些事情？

问题描述

一般问题

我的 python 云函数每秒引发大约 0.05 个内存错误 - 它每秒被调用大约 150 次。我感觉我的函数会留下内存残留，这会导致它的实例在处理了许多请求后崩溃。您应该做或不做哪些事情，以使您的函数实例在每次调用时都不会吃掉“更多分配的内存”？我被指给文档了解我应该删除所有临时文件，因为这是写在内存中的，但我认为我没有写过任何文件。

编辑：代码摘录和更多上下文

这些请求包含有助于在电子商务网站上实现跟踪的参数。现在我复制了它，可能会有一个反模式，我form['products']在迭代它时会修改它，但我认为这与内存浪费没有任何关系？

from json import dumps
from datetime import datetime
from pytz import timezone

from google.cloud import storage
from google.cloud import pubsub
from google.cloud import error_reporting

from unidecode import unidecode

# this is done in global context because I only want to load the BOTS_LIST at
# cold start
PROJECT_ID = '...'
TOPIC_NAME = '...'
BUCKET_NAME = '...'
BOTS_PATH = '.../bots.txt'
gcs_client = storage.Client()
cf_bucket = gcs_client.bucket(BUCKET_NAME)
bots_blob = cf_bucket.blob(BOTS_PATH)
BOTS_LIST = bots_blob.download_as_string().decode('utf-8').split('\r\n')
del cf_bucket
del gcs_client
del bots_blob

err_client = error_reporting.Client()


def detect_nb_products(parameters):
    '''
    Detects number of products in the fields of the request.
    '''
    # ...


def remove_accents(d):
    '''
    Takes a dictionary and recursively transforms its strings into ASCII
    encodable ones
    '''
    # ...


def safe_float_int(x):
    '''
    Custom converter to float / int
    '''
    # ...


def build_hit_id(d):
    '''concatenate specific parameters from a dictionary'''
    # ...


def cloud_function(request):
    """Actual Cloud Function"""
    try:
        time_received = datetime.now().timestamp()
        # filtering bots
        user_agent = request.headers.get('User-Agent')
        if all([bot not in user_agent for bot in BOTS_LIST]):
            form = request.form.to_dict()
            # setting the products field
            nb_prods = detect_nb_products(form.keys())
            if nb_prods:
                form['products'] = [{'product_name': form['product_name%d' % i],
                                     'product_price': form['product_price%d' % i],
                                     'product_id': form['product_id%d' % i],
                                     'product_quantity': form['product_quantity%d' % i]}
                                    for i in range(1, nb_prods + 1)]

            useful_fields = [] # list of keys I'll keep from the form
            unwanted = set(form.keys()) - set(useful_fields)
            for key in unwanted:
                del form[key]

            # float conversion
            if nb_prods:
                for prod in form['products']:
                    prod['product_price'] = safe_float_int(
                        prod['product_price'])

            # adding timestamp/hour/minute, user agent and date to the hit
            form['time'] = int(time_received)
            form['user_agent'] = user_agent
            dt = datetime.fromtimestamp(time_received)
            form['date'] = dt.strftime('%Y-%m-%d')

            remove_accents(form)

            friendly_names = {} # dict to translate the keys I originally
            # receive to human friendly ones
            new_form = {}
            for key in form.keys():
                if key in friendly_names.keys():
                    new_form[friendly_names[key]] = form[key]
                else:
                    new_form[key] = form[key]
            form = new_form
            del new_form

            # logging
            print(form)

            # setting up Pub/Sub
            publisher = pubsub.PublisherClient()
            topic_path = publisher.topic_path(PROJECT_ID, TOPIC_NAME)
            # sending
            hit_id = build_hit_id(form)
            message_future = publisher.publish(topic_path,
                                               dumps(form).encode('utf-8'),
                                               time=str(int(time_received * 1000)),
                                               hit_id=hit_id)
            print(message_future.result())

            return ('OK',
                    200,
                    {'Access-Control-Allow-Origin': '*'})
        else:
        # do nothing for bots
            return ('OK',
                    200,
                    {'Access-Control-Allow-Origin': '*'})
    except KeyError:
        err_client.report_exception()
        return ('err',
                200,
                {'Access-Control-Allow-Origin': '*'})

标签： pythongoogle-cloud-functions

解决方案

您可以尝试一些事情（理论上的答案，我还没有玩过 CF）：

显式删除您在机器人处理路径上分配的临时变量，这些变量可能相互引用，从而阻止内存垃圾收集器释放它们（请参阅https://stackoverflow.com/a/33091796/4495081）：nb_prods、、、、, , 例如。unwantedformnew_formfriendly_names
如果unwanted总是相同，则改为全局。
form在将其重新分配给之前删除new_form（旧form对象仍然存在）；由于new_form对象仍然由form. 即改变：
```
    form = new_form
    del new_form
```
进入
```
    del form
    form = new_form
```
在发布主题后和返回之前显式调用内存垃圾收集器。我不确定这是否适用于 CF 或调用是否立即生效（例如在 GAE 中它不是，请参阅在 App Engine 后端实例上完成请求后何时释放内存？）。这也可能是矫枉过正，并可能会损害您 CF 的表现，看看它是否/如何为您工作。
```
gc.collect()
```

python - 为了避免内存泄漏，我应该在我的 python 云函数中避免哪些事情？

问题描述

一般问题

更多上下文

编辑：代码摘录和更多上下文

解决方案

推荐阅读