Revision as of 02:29, 31 May 2010

Please view Performance/load_performance_implement about implement. This document explain parallel and dead lock problem and resolve plan.

Problem

Now I'd finished the part of odf impress's code, and wish is:

settings.xml when processing the <office:settings> element, it's subelement will be parallel processed.

styles.xml when processing the <office:styles> and <office:automatic-styles> and <office:master-styles> elements, it's subelement will be parallel processed.

content.xml when processing the <office:presentation> and styles's elements, it's subelement will be parallel processed.

When running, that will dead lock.

Analysis

We can understand OOo had three type mutex.

• Global Mutex: It can be get from osl::Mutex::getGlobalMutex(), and can be used at a simple critical which lock section no other mutex.

• Solar Mutex: It can be get from Application::GetSolarMutex(), and can be used any where. which lock section can had other mutex, and can be spin lock. It's used at the uno implement class's method section, main function is synchronization UNO environment.

• General Mutex: It can be used other thread and OOo main thread, etc. Which can be as same type.

So, Dead lock will be, It like this:

Solve A plan

• The First: So we must let the 'Solar Mutex' will not acquire at parallel section, It is ease.

But there will synchronization problem; where the base struct like svarray(svl) and std::vector etc. be there.

• The Second: We must let the 'Solar Mutex' synchronization at parallel section, so there are an other mutex object.

So we can design 'Solar Mutex' has two mutex objects, One synchronize at general section and One synchronize at parallel section. How 'Solar Mutex' can know it is general or parallel section; there are function omp_in_parallel() in OpenMP . Now It like this:

Ok, that seem is right, Yes it not wrong. But performance no improve. I think it is that the synchronize section is much block. So the processing is multithread, But all most time only one thread can runing, and other thread is block.

So I design the new mutex model, and will test it right or no.