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How to automatically generate a stacktrace when my program crashes
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For Linux and I believe Mac OS X, if you're using gcc, or any compiler that uses glibc, you can use the backtrace() functions in execinfo.h to print a stacktrace and exit gracefully when you get a segmentation fault. Documentation can...
Multiprocessing vs Threading Python [duplicate]
I am trying to understand the advantages of multiprocessing over threading . I know that multiprocessing gets around the Global Interpreter Lock, but what other advantages are there, and can threading not do the same thing?
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mongodb group values by multiple fields
...takes an "pipeline" expression as an argument instead of the "localFields" and "foreignFields" options. This then allows a "self-join" with another pipeline expression, in which we can apply $limit in order to return the "top-n" results.
db.books.aggregate([
{ "$group": {
"_id": "$addr",
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Filtering for empty or NULL names in a queryset
...e.objects.exclude(alias__isnull=True)
If you need to exclude null values and empty strings, the preferred way to do so is to chain together the conditions like so:
Name.objects.exclude(alias__isnull=True).exclude(alias__exact='')
Chaining these methods together basically checks each condition i...
How to pass a user defined argument in scrapy spider
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Spider arguments are passed in the crawl command using the -a option. For example:
scrapy crawl myspider -a category=electronics -a domain=system
Spiders can access arguments as attributes:
class MySpider(scrapy.Spider):
name = 'myspider'
def __init__(self,...
Show current assembly instruction in GDB
... that it shows the current source line? The default output after every command looks like this:
7 Answers
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Shared-memory objects in multiprocessing
...r array), place that in shared memory, wrap it with multiprocessing.Array, and pass that to your functions. This answer shows how to do that.
If you want a writeable shared object, then you will need to wrap it with some kind of synchronization or locking. multiprocessing provides two methods of do...
What is the difference between save and insert in Mongo DB?
What is the difference between save and insert in Mongo DB?
both looks the same
9 Answers
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How to process SIGTERM signal gracefully?
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This is the best answer (no threads required), and should be the preferred first-try approach.
– jose.angel.jimenez
Oct 12 '15 at 16:56
2
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How to remove an element from a list by index
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Use del and specify the index of the element you want to delete:
>>> a = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> del a[-1]
>>> a
[0, 1, 2, 3, 4, 5, 6, 7, 8]
Also supports slices:
>>> del a[2:4]
>...