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Create an index on a huge MySQL production table without table locking
...able users add index ddopsonfu (last_name, email, first_name, confirmation_token, current_sign_in_ip);'
echo "Index Update - FINISH"
sleep 0.05
kill $PID
time mysql -uroot website_development -e 'drop index ddopsonfu on users;'
My Server (InnoDB):
Server version: 5.5.25a Source distribution
Out...
How to correctly implement custom iterators and const_iterators?
...
You need to edit your answer. Assuming m_data was allocated with m_size elements you get Undefined Behavior: m_data[m_size] is UB. You can simply fix it by replacing it with m_data+m_size. For reverse iterators, both m_data[-1] and m_data-1 are incorrect (UB). To fix reverse...
What's the difference between SoftReference and WeakReference in Java?
...object is phantomly referenced after it has been finalized, but before its allocated memory has been reclaimed.
Source
Analogy: Assume a JVM is a kingdom, Object is a king of the kingdom, and GC is an attacker of the kingdom who tries to kill the king(object).
When King is Strong, GC can not k...
Is Fortran easier to optimize than C for heavy calculations?
...ers will most likely return that struct in sret form with the caller stack allocating space, passing a pointer to the callee that fills it in. That is several times slower than returning multiple values in registers as a Fortran compiler would. Note that C99 fixed this in the special case of complex...
Dynamic type languages versus static type languages
...mpiler can use this. If we in Java do "string" + "string" or 3 + 3, both + tokens in text in the end represent a completely different operation and datum, the compiler knows which to choose from the types alone.
Now, I'm going to make a very controversial statement here but bear with me: 'dynamic ty...
Markup XML解析库下载（Markup.h 和 Markup.cpp） - 源码下载 - 清泛网 - 专注C/C++及内核技术
...L ftell
#define MCD_INTFILEOFFSET long
#endif
struct FilePos;
struct TokenPos;
struct NodePos;
struct PathPos;
struct SavedPosMapArray;
struct ElemPosTree;
class CMarkup
{
public:
CMarkup() { x_InitMarkup(); SetDoc( NULL ); };
CMarkup( MCD_CSTR szDoc ) { x_InitMarkup(); SetDoc( sz...
What are fixtures in programming?
...tate a method with @org.junit.After to release any permanent resources you allocated in setUp
For example, to write several test cases that want to work with different combinations of 12 Swiss Francs, 14 Swiss Francs, and 28 US Dollars, first create a fixture:
public class MoneyTest {
private M...
Use numpy array in shared memory for multiprocessing
... size of the Array. Think of it as a shared block of memory that had to be allocated before child processes are started. You don't need to use all the memory e.g., you could pass count to numpy.frombuffer(). You could try to do it on a lower level using mmap or something like posix_ipc directly to i...
How do you know when to use fold-left and when to use fold-right?
... // third stack frame
// (I don't remember if the JVM allocates space
// on the stack for the third frame as well)
while List(1,2,3).foldLeft(0)(_ + _) would reduce to:
(((0 + 1) + 2) + 3)
which can be iteratively computed, as done in the implementation of List.
In a str...
What is an existential type?
..., because no identifier has been bound to it. (The ? wildcard is a special token, not an identifier that "captures" a type.) t.value has effectively become opaque; perhaps the only thing you can still do with it is type-cast it to Object.
Summary:
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