我正在编写的一些分析代码之上构建一个接口,用于执行一些 SQL 并处理查询结果。我想向用户公开此分析代码中围绕许多事件的日志记录。因为分析代码运行时间相当长,并且因为我不希望 UI 阻塞,所以到目前为止我已经通过将分析函数放入其自己的线程中来完成此操作。
我现在拥有的简化示例(完整脚本):
import sys
import time
import logging
from PySide2 import QtCore, QtWidgets
def long_task():
logging.info('Starting long task')
time.sleep(3) # this would be replaced with a real task
logging.info('Long task complete')
class LogEmitter(QtCore.QObject):
sigLog = QtCore.Signal(str)
class LogHandler(logging.Handler):
def __init__(self):
super().__init__()
self.emitter = LogEmitter()
def emit(self, record):
msg = self.format(record)
self.emitter.sigLog.emit(msg)
class LogDialog(QtWidgets.QDialog):
def __init__(self, parent=None):
super().__init__(parent)
log_txt = QtWidgets.QPlainTextEdit(self)
log_txt.setReadOnly(True)
layout = QtWidgets.QHBoxLayout(self)
layout.addWidget(log_txt)
self.setWindowTitle('Event Log')
handler = LogHandler()
handler.emitter.sigLog.connect(log_txt.appendPlainText)
logger = logging.getLogger()
logger.addHandler(handler)
logger.setLevel(logging.INFO)
class Worker(QtCore.QThread):
results = QtCore.Signal(object)
def __init__(self, func, *args, **kwargs):
super().__init__()
self.func = func
self.args = args
self.kwargs = kwargs
def run(self):
results = self.func(*self.args, **self.kwargs)
self.results.emit(results)
class MainWindow(QtWidgets.QMainWindow):
def __init__(self):
super().__init__()
widget = QtWidgets.QWidget()
layout = QtWidgets.QHBoxLayout(widget)
start_btn = QtWidgets.QPushButton('Start')
start_btn.clicked.connect(self.start)
layout.addWidget(start_btn)
self.setCentralWidget(widget)
self.log_dialog = LogDialog()
self.worker = None
def start(self):
if not self.worker:
self.log_dialog.show()
logging.info('Run Starting')
self.worker = Worker(long_task)
self.worker.results.connect(self.handle_result)
self.worker.start()
def handle_result(self, result=None):
logging.info('Result received')
self.worker = None
if __name__ == '__main__':
app = QtWidgets.QApplication()
win = MainWindow()
win.show()
sys.exit(app.exec_())
这工作得很好,只是我需要能够允许用户停止分析代码的执行。我读过的所有内容都表明没有办法很好地中断线程,因此使用multiprocessing
库似乎是可行的方法(无法重新编写分析代码以允许定期轮询,因为大部分时间都花在等待查询返回结果上)。通过使用不阻塞 UI 的方式执行分析代码,可以很容易地获得相同的功能multiprocessing.Pool
and apply_async
.
例如。替换MainWindow
从上面:
class MainWindow(QtWidgets.QMainWindow):
def __init__(self):
super().__init__()
widget = QtWidgets.QWidget()
layout = QtWidgets.QHBoxLayout(widget)
start_btn = QtWidgets.QPushButton('Start')
start_btn.clicked.connect(self.start)
layout.addWidget(start_btn)
self.setCentralWidget(widget)
self.log_dialog = LogDialog()
self.pool = multiprocessing.Pool()
self.running = False
def start(self):
if not self.running:
self.log_dialog.show()
logging.info('Run Starting')
self.pool.apply_async(long_task, callback=self.handle_result)
def handle_result(self, result=None):
logging.info('Result received')
self.running = False
但我似乎无法弄清楚如何从子进程检索日志输出并将其传递给父进程以更新日志对话框。我已经阅读了几乎所有关于此问题的问题以及如何处理从多个进程写入单个日志文件的食谱示例,但我无法集中注意力如何使这些想法适应我的想法我想在这里做。
Edit
因此,试图弄清楚为什么我看到的行为与我添加的 @eyllanesc 不同:
logger = logging.getLogger()
print(f'In Func: {logger} at {id(logger)}')
and
logger = logging.getLogger()
print(f'In Main: {logger} at {id(logger)}')
to long_task
and Mainwindow.start
, 分别。当我跑步时main.py
I get:
In Main: <RootLogger root (INFO)> at 2716746681984
In Func: <RootLogger root (WARNING)> at 1918342302352
这似乎是中描述的这个问题 https://stackoverflow.com/questions/34724643/python-logging-with-multiprocessing-root-logger-different-in-windows
这个想法使用一个Queue
and QueueHandler
虽然作为一个解决方案似乎类似于@eyllanesc的原始解决方案