Bug #41233 Using few large TS data files can cause tmp deadlock error under load

Description:
When first testing DD using NDB Atomics (NDB API Performance Application) I would receive back test failures due to deadlock messages. 

The program was packaging 900 random updates into a single transaction focused on a single table of 10,000,000 rows.

The TS data files consisted of 2 data files with the size of 2GB.

To get around this, Tomas suggested creating many small sized data files allowing for additional reader threads.

I created 40 data files sized 50MB each. This did work around the temp deadlock errors that I had been getting  

How to repeat:
Easy to repeat with ACRT after modifying the loader script to create 2 data files at 2GB each and then using NDBAtomics to run the load.

Suggested fix:
Allowing additional reader threads per data file or ensuring deadlocks can not happen when using large files

Jeb,

this has been fixed in 6.4
(and won't be backported)

can you retest with 6.4?

/Jonas

dont know what to do

Hi,

I was able to repeat the test today and received the following during "Random Updates":

Error in Atomics.cpp, line: 460, code: 266, msg: Time-out in NDB, probably caused by deadlock.

I did have DiskIOThreadPool=2

The code at line 460:

        //Execute to retrieve the data, but do not commit so we keep
        // our lock on that row
        if (m_pMyTrans->execute( NdbTransaction::NoCommit) == -1 ){
line 460->APIERROR(m_pMyTrans->getNdbError());
          pMyNdb->closeTransaction(m_pMyTrans);
          return 1;
        }

Please note that the code does ensure that during the "Random Updates" we are not reusing the same PK in the batch of operational updates:

for (int h = 0; h < this->GetGroupNumber(); h++){
  accountIdTableCounter = h;
  while (idFound){
    idFound = false;
     for (int i = 0; i < accountIdTableCounter; i++){
       if (accountIdTable[i] == nAccountID){
         idFound = true;
         this->MakeData();
         break;
       }
     }
  }

I will break this down to an easy test case next week if "Okayed" by Manager.