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Lock, mutex, semaphore… what's the difference?
... number of cpu, io or ram intensive tasks running at the same time.
For a more detailed post about the differences between mutex and semaphore read here.
You also have read/write locks that allows either unlimited number of readers or 1 writer at any given time.
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Running script upon login mac [closed]
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Design Patterns: Factory vs Factory method vs Abstract Factory
...ional patterns:
Design start out using Factory Method (less complicated, more customizable, subclasses proliferate) and evolve toward Abstract Factory, Prototype, or Builder (more flexible, more complex) as the designer discovers where more flexibility is needed
Abstract Factory classes are ofte...
Get exit code of a background process
...ing. (ps | grep isn't idiot-proof. If you have time you can come up with a more robust way to tell whether the process is still running).
Here's a skeleton script:
# simulate a long process that will have an identifiable exit code
(sleep 15 ; /bin/false) &
my_pid=$!
while ps | grep " $my_pid ...
Shiro vs. SpringSecurity [closed]
...eem like it is making security easier to implement, Shiro seems to be much more coherent and easier to understand. I am looking for lists of pros and cons between these two frameworks.
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What is the largest Safe UDP Packet Size on the Internet
...t said; having less fragments makes delivery "safer" because if there were more than one and any one of those never made it - the whole packet (datagram) is dropped by UDP.
– markmnl
Jan 5 '13 at 9:28
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xpath find if node exists
... is no xsl equivalent to if-then-else, so if you are looking for something more like an if-then-else, you're normally better off using xsl:choose and xsl:otherwise. So, Patrick's example syntax will work, but this is an alternative:
<xsl:choose>
<xsl:when test="/html/body">body node ex...
Parsing HTML into NSAttributedText - how to set font?
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How to count the number of set bits in a 32-bit integer?
...ith a few clever optimizations. Continuing on with the same pattern for 2 more steps can widen to 2x 16-bit then 1x 32-bit counts. But there is a more efficient way on machines with fast hardware multiply:
Once we have few enough "elements", a multiply with a magic constant can sum all the element...
How to start a background process in Python?
I'm trying to port a shell script to the much more readable python version. The original shell script starts several processes (utilities, monitors, etc.) in the background with "&". How can I achieve the same effect in python? I'd like these processes not to die when the python scripts complete. I ...