Bug #96551 Memory leak in mysql server 8.0 ndb nodejs
Submitted: 15 Aug 12:25 Modified: 15 Aug 18:44
Reporter: Xing Ai (OCA) Email Updates:
Status: Verified Impact on me:
None 
Category:MySQL Cluster: NDB API Severity:S3 (Non-critical)
Version:8.0 OS:Any
Assigned to: CPU Architecture:Any
Tags: 8.0, memory leak, ndb, NodeJS

[15 Aug 12:25] Xing Ai
Description:
This memory leak problem is found through code review instead of testing.

C++ source file: https://github.com/mysql/mysql-server/blob/8.0/storage/ndb/nodejs/jones-ndb/impl/src/ndb/Q....

From the source file, if we look at code snippet below, the memory of "buffers[level].buffer" is allocated with "new char[]", however in the class's destructor, there is no loop to deallocate such memory.

How to repeat:
Here is the code snippet for the constrctor, destructor and member function "createRowBuffer(...)" which have memory management.

QueryOperation::QueryOperation(int sz) :
  size(sz),
  buffers(new QueryBuffer[sz]),
  // ...
{
  ndbQueryBuilder = NdbQueryBuilder::create();
  DEBUG_PRINT("Size: %d", size);
}

QueryOperation::~QueryOperation() {
  ndbQueryBuilder->destroy();
  delete[] buffers;
  free(results);
}

void QueryOperation::createRowBuffer(int level, Record *record, int parent_table) {
  buffers[level].record = record;
  buffers[level].buffer = new char[record->getBufferSize()];
  buffers[level].size   = record->getBufferSize();
  buffers[level].parent = (short) parent_table;
}

Suggested fix:
The destructor needs to add code to deallocate the memory for "buffers[level].buffer".

QueryOperation::~QueryOperation() {
  ndbQueryBuilder->destroy();
  for (int i = 0; i < size; i++)
  {
    delete[] buffers[i].buffer;
  }
  delete[] buffers;
  free(results);
}
[15 Aug 18:44] Bogdan Kecman
Hi,

Looks like you are right, thanks for the report.

all best
Bogdan