PM2不记录Python3打印语句 [英] PM2 doesn't log Python3 print statements

问题描述

我正在使用PM2在后台运行Python程序

I'm using PM2 to run a Python program in the background like so

pm2 start helloworld.py

，并且效果很好.但是，在helloworld.py中，我有几个用作日志的打印语句.例如，当出现网络请求或数据库值已更新时.当我像这样运行helloworld.py时:

and it works perfectly fine. However, within helloworld.py I have several print statements that act as logs. For example, when a network request comes in or if a database value is updated. When I run helloworld.py like so:

python3 helloworld.py

所有这些打印语句都是可见的，我可以调试我的应用程序.但是，运行时

all these print statements are visible and I can debug my application. However, when running

pm2 logs helloworld

这些打印语句均未显示.

none of these print statements show up.

推荐答案

这个问题已有几个月的历史了，所以也许您在不久前就发现了这个问题，但是当我遇到相同的问题时，它是Google热门搜索之一问题，所以我想我要添加发现的内容.

This question is a few months old, so maybe you figured this out a while ago, but it was one of the top google hits when I was having the same problem so I thought I'd add what I found.

似乎是python如何缓冲sys.stdout的问题.在某些平台/实例中，当由pm2或nohup调用时，sys.stdout流可能不会刷新，直到进程退出.将"-u"参数传递给python解释器可阻止其缓冲sys.stdout.在pm2的process.json文件中，我添加了"interpreter_args":-u"，现在我可以正常获取日志了.

Seems like it's an issue with how python buffers sys.stdout. In some platforms/instances, when called by say pm2 or nohup, the sys.stdout stream may not get flushed until the process exits. Passing the "-u" argument to the python interpreter stops it from buffering sys.stdout. In the process.json for pm2 I added "interpreter_args": "-u" and I'm getting logs normally now.

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