Haskell HDBC-ODBC Memory Leak?

Question

When using the Haskell HDBC-ODBC library to connect to a Microsoft SQL Server I am experiencing a bad memory leak.

import           Database.HDBC        
import qualified Database.HDBC.ODBC   as ODBC
import           Control.Monad

-- | Main application.
main :: IO ()
main = dbTest

dbTest :: IO ()
dbTest = do
    let connStr = "DSN=TESTDB;Uid=sa;Pwd=password"
    conn <- ODBC.connectODBC connStr
    replicateM_ 20000 (loop conn)
    disconnect conn
  where
    loop c = do
        result <- getTables c
        commit c
        putStrLn $ show result

Running the heap profiler gives me constant memory usage but Window reports memory increasing to almost 100MB of usage.

http://i.stack.imgur.com/YkUTW.png

To me this seems like the memory leak is in the Foreign Function interface of the ODBC driver, but this is my first time profiling code so I can't be certain. Does anyone have any further insight or suggestions for a fix? Calling System.Mem.performGC in the loop to try and clean up has no effect.

Are there any alternatives to using HDBC-ODBC? If not, I might need to learn F#.

Answer 1

The issue was in the hdbc-odbc library. A new version v2.5 is available from the Git repo but the hdbc library also needs to be patched to work.

More details available at this bug report.