在windows上，可以通过控制面板，查看软件安装情况。那么除此之外还有其它方法吗？

 

PS C:\Users\wyq> Get-WmiObject -class Win32_Product |Select-Object -Property name,version

name                                                                                                 version
----                                                                                                 -------
Microsoft Visual C++ Compiler Package for Python 2.7                                                 9.0.1.30729
Microsoft .NET Framework 4.5.1 Multi-Targeting Pack                                                  4.5.50932
Microsoft Visual C++  x64-x86 Cross Compilers - CHS Resources                                        12.0.21005
Microsoft SQL Server 2012 T-SQL Language Service                                                     11.1.3000.0
....

 

subprocess.Popen(cmd, close_fds=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)

 

ValueError: close_fds is not supported on Windows platforms if you redirect stdin/stdout/stderr

 

在windows上subprocess.Popen的参数close_fds=True与stdin/stdout/stderr不能共存

 

* 多行字符串拼接使用小括号

 

s = ('select *'
     'from atable'
     'where id=888')
print s, type(s)

#输出
select *from atablewhere id=888 <type 'str'>

 

* python遇到未闭合的小括号，自动将多行拼接为一行,相比三个引号和换行符，这种方式不会把换行符、前导空格当作字符。

 

get-childitem * -include *.pyc -recurse |remove-item

ls * -include *.pyc -recurse |rm

32位python在windows上调用命令行(os.system或subprocess.Popen)。执行后，如果返回码太大，python取得的返回值也是0。此时无法判断执行成功还是失败，这个是32位python的bug。

 

以时间同步命令w32tm位例子

C:\WINDOWS\system32>w32tm /resync
发生下列错误: 服务尚未启动。 (0x80070426)

C:\WINDOWS\system32>echo %errorlevel%
-2147023834

>>> os.system("w32tm /resync")
发生下列错误: 服务尚未启动。 (0x80070426)
-2147023834

>>> os.system("w32tm /resync")
发生下列错误: 服务尚未启动。 (0x80070426)
0

注意：此时命令执行错误的返回码也是0。

通常成功返回码才是0，这里执行错误，返回码却是也0。当要判断执行成功还失败时，这里便是个坑。

https://docs.python.org/2/library/os.html

 

runas /noprofile /user:Administrator cmd

 

修改：     "data/python\345\255\246\344\271\240\350\265\204\346\226\231.wiki"

git config --global core.quotepath false

显示正常

 

在tornado中用apscheduler实现计划任务，出现错误提示

 

2015-12-04 19:10:22,227 - apscheduler.scheduler - WARNING - Execution of job "TaskHandle.progress_job (trigger: date[2015-12-04 19:10:22 CST], next run at: 2015-12-04 19:10:22 CST)" skipped: maximum number of running instances reached (1)

缺乏资料，所以根据提示，分析apscheduler源码

在源码目录下，搜索关键字maxinum，找到记录异常的位置

#apscheduler/schedulers/base.py
if run_times:
    try:
        executor.submit_job(job, run_times)
    except MaxInstancesReachedError:
        self._logger.warning(
            'Execution of job "%s" skipped: maximum number of running instances reached (%d)',
            job, job.max_instances)
    except:
        self._logger.exception('Error submitting job "%s" to executor "%s"', job, job.executor)

 

继续看submit_job函数，找到异常抛出位置

#apscheduler/executors/base.py
def submit_job(self, job, run_times):
    """
    Submits job for execution.

    :param Job job: job to execute
    :param list[datetime] run_times: list of datetimes specifying when the job should have been run
    :raises MaxInstancesReachedError: if the maximum number of allowed instances for this job has been reached
    """

    assert self._lock is not None, 'This executor has not been started yet'
    with self._lock:
        if self._instances[job.id] >= job.max_instances:
            raise MaxInstancesReachedError(job)

        self._do_submit_job(job, run_times)
        self._instances[job.id] += 1

在submit_job(提交任务)时加1，在_run_job_success(任务运行成功)时减1。 当self._instances[job.id]大于job.max_instances抛出异常。

max_instances默认值为1，它表示id相同的任务实例数。

通过设置max_instances参数

sched.add_job(child_job, max_instances=10, trigger=DateTrigger(), id="123")

import time
import tornado.ioloop
from apscheduler.triggers.date import DateTrigger
from apscheduler.schedulers.tornado import TornadoScheduler

sched = TornadoScheduler()

def child_job():
    print "start"
    time.sleep(60)
    print "end"

def main_job():
    sched.add_job(child_job, trigger=DateTrigger(), id="123")

sched.add_job(main_job, 'interval', seconds=5)

sched.start()
tornado.ioloop.IOLoop.instance().start()

job_id: 7279209ab6c2498698f2117bb97e18a1, instances: 0, max_instances: 1
job_id: 123, instances: 0, max_instances: 1
start
job_id: 7279209ab6c2498698f2117bb97e18a1, instances: 0, max_instances: 1
job_id: 123, instances: 1, max_instances: 1
WARNING:apscheduler.scheduler:Execution of job "child_job (trigger: date[2015-12-07 15:27:11 CST], next run at: 2015-12-07 15:27:11 CST)" skipped: maximum number of running instances reached (1)
job_id: 7279209ab6c2498698f2117bb97e18a1, instances: 0, max_instances: 1