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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...
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]
>...
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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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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What integer hash function are good that accepts an integer hash key?
... a multiplier that is in the order of your hash size (2^32 in the example) and has no common factors with it. This way the hash function covers all your hash space uniformly.
Edit: The biggest disadvantage of this hash function is that it preserves divisibility, so if your integers are all divisibl...
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,...
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...
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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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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How to write a Python module/package?
I've been making Python scripts for simple tasks at work and never really bothered packaging them for others to use. Now I have been assigned to make a Python wrapper for a REST API. I have absolutely no idea on how to start and I need help.
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