Architecture/Proposal/Advanced Threading-Architecture

From Apache OpenOffice Wiki
Jump to: navigation, search

Type: Proposal State: draft

The advanced threading-architecture aims to solve OOos scalability and responsiveness problems.


A brief list of problems we face:

  • Sometimes unresponsive user interface, e.g. trying to connect to a particular web server may take some minutes, without repaint and everything (it can take more time, if you have more than one http:// reference in your document) ;-).
  • Polling / busy waiting, e.g. frequent re-schedule or yield calls, while loading or saving a document.
  • Scalability with multiple clients doing API calls, only one API call can be in execution at any time.
  • Most long lasting operations such as loading, saving, printing etc. are not interruptible.


OOo must be changed to be purely event / callback driven. Please see Wikipedia for what event-driven programming is.

The following list gives a first idea, of what should be done,

  • all (potentially) blocking calls need to be event-driven,
  • all long lasting calls need to be executed by dedicated threads, notifying the consumers via events / callbacks, in case data is available (thus basically creating event sources and event sinks),
  • UNIX asynchronous signals, being an process interface by their own, need to be mapped to events,
  • Windows window messages need to be mapped to events,
  • the threading-architecture must be defined high level, e.g.
    • concurrency per application, or
    • concurrency per document.


  • Not calling potential blocking system calls leads to 'short' lasting mutex acquisitions.
  • No hand crafted reschedules necessary anymore.
  • Easy utilization of hyper threading, multiple cores and SMP.
  • Controllable CPU utilization and possible avoidance of over utilization.
  • 'Simple' architecture.
  • Potentially high level thread abstraction.


  • (assumed to be) Hard to implement.

Pseudo Code for event loop:

void dispatch(int signal) {
  switch(signal) {
  case SIGIO:
  case SIGTERM:
int quit;
sigset_t sigset;
int main(void) {
  int signal;
  while(!quit) {
    sigwait(&sigset, &signal);
  return 0;

Graphical overview:
Spec Architecture Threading Advanced.jpg

Personal tools