Problems using the .NET transactionscope with DB2 on a 64 bit machine

To solve the growing need for more memory, we decided to upgrade all our development machines to a 64bit OS. Although this allows us to install and use more memory on our machines, it also introduces a whole list of new problems.

One of them was regarding the usage of the .NET transactionscope in combination with DB2. In DB2 managing your transactions through the transactionscope will immediatelly involve the DTC coordinator. However the moment the DTC tries to open a transaction, it fails with the following error message:

The XA Transaction Manager attempted to load the XA resource manager DLL. The call to LOADLIBRARY for the XA resource manager DLL failed: DLL=C:\Program Files\IBM\SQLLIB\BIN\DB2APP.DLL, HR=0x800700c1, File=d:\w7rtm\com\complus\dtc\dtc\xatm\src\xarmconn.cpp Line=2446.

After trying almost every possible solution, we finally found a solution that worked for us. When installing the DB2 client, it doesn’t correctly register the 64bit dll’s in the register.

The following registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\MSDTC\XADLL incorrectly referenced the db2app.dll instead of the db2app64.dll. As a consequence the MSDTC tries to load a 32bit DLL on 64bit machine, which fails. After changing the reference to the 64bit dll everything worked.

More information in this thread on the DB2 forums.

Podman– Command execution failed with exit code 125

After updating WSL on one of the developer machines, Podman failed to work. When we took a look through Podman Desktop, we noticed that Podman had stopped running and returned the following error message: Error: Command execution failed with exit code 125 Here are the steps we tried to fix the issue: We started by running podman info to get some extra details on what could be wrong: >podman info OS: windows/amd64 provider: wsl version: 5.3.1 Cannot connect to Podman. Please verify your connection to the Linux system using `podman system connection list`, or try `podman machine init` and `podman machine start` to manage a new Linux VM Error: unable to connect to Podman socket: failed to connect: dial tcp 127.0.0.1:2655: connectex: No connection could be made because the target machine actively refused it. That makes sense as the podman VM was not running. Let’s check the VM: >podman machine list NAME ...

Cache stampede: when our cache turned against us

While investigating some performance issues, we ran into an ASP.NET Core API that cached a fairly expensive aggregation query for 60 seconds. Under normal load, that was fine: one request rebuilds the cache, everyone else reads from it. Under peak load, dozens of requests would arrive in that same expiry window, all see a cache miss, and all fire the same expensive query in parallel. The database didn't like that. That was the moment when our caching layer stopped helping and started hurting. A burst of requests comes in at the same time, all miss the cache, and all go hammer the database or the downstream API at once. That's a cache stampede . The cache was supposed to protect our backend, and for a few hundred milliseconds it did the opposite. Why this happens IMemoryCache.GetOrCreate (and its async sibling) looks like it protects you, but it doesn't add any locking on its own. Look at the naive version: public async Task<Report> GetReportAsync(string key) ...

Azure DevOps/ GitHub emoji

I’m really bad at remembering emoji’s. So here is cheat sheet with all emoji’s that can be used in tools that support the github emoji markdown markup: All credits go to rcaviers who created this list.

The art of simplicity

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