Data allocation

Here are some tips for allocating data with performance in mind.

  • Reserve size of arrays to reduce reallocation:
    When you add elements to an SPL collective type, you can sometimes preallocate the size of the object: Here is an example with a list:
    SPL::list myList;
....
myList.reserve(numElements);  // preallocate large enough
for (...) {
  ....
  myList.push_back(newElem);  // no reallocation necessary
}
  • Declare class member objects
    A bad example is when otuple is constructed during each operator invocation 
    OPort0Type otuple;      // otuple is local variable
otuple.set_attr …
submit(otuple, 0);
    A better is example is to declare otuple as a member in the operator's class.
    Use the following guidelines when you declare a tuple as a member in the operator's class:
    • When the operator's process method can be called concurrently, use AutoMutex to protect the state against concurrent accesses.
    • After a tuple is submitted to a mutating port, the tuple must not be modified. Before a tuple is submitted to a mutating port, it might be helpful to make a copy of the tuple.