{"id":5714,"date":"2019-02-27T17:19:11","date_gmt":"2019-02-28T01:19:11","guid":{"rendered":"https:\/\/www.coretechnologies.com\/blog\/?p=5714"},"modified":"2025-12-08T06:43:39","modified_gmt":"2025-12-08T14:43:39","slug":"vb6-memory-leaks","status":"publish","type":"post","link":"https:\/\/www.coretechnologies.com\/blog\/alwaysup\/vb6-memory-leaks\/","title":{"rendered":"Q&A: How do I Make AlwaysUp Babysit my “Leaky” VB6 Program?"},"content":{"rendered":"
\"Q<\/div>\n
\n  Our old VB6<\/a> program leaks memory on every request and it can fail or crash multiple times a day. We need to re-write it but we don’t have budget right now so I’m looking at AlwaysUp<\/a> to run it all the time. What settings should I use to keep it running?<\/p>\n

— Anonymous<\/p>\n<\/div>\n

Hi. We have many customers who have turned to AlwaysUp to keep legacy applications going. Here is what we recommend for your situation:<\/p>\n

\n
\n
\"\"<\/a><\/div>\n<\/div>\n

Restart your VB6 program on high memory use<\/h2>\n

AlwaysUp is designed to launch your application as a Windows Service when your computer boots, but it can perform several “monitoring tasks” after that initial event.<\/p>\n

One such task is to watch how much memory your application is using. You can setup AlwaysUp to stop and restart your application when its memory usage crosses a specific threshold.<\/p>\n

The setting is available on AlwaysUp’s Monitor tab:<\/p>\n

\"AlwaysUp<\/a><\/div>\n

The default threshold is 512 MB. Is that too much (or too little) for your VB6 application?<\/p>\n

We suggest using the Task Manager to get an idea of how much memory your application typically consumes. Use that information to set the threshold appropriately.<\/p>\n

Note: Because AlwaysUp is a 32-bit application, the maximum memory threshold you can set is 4 GB. You will have to configure the CheckMemorySize64 sanity check plugin<\/a> to exceed that limit. Please get in touch<\/a> if you need help doing that.<\/p>\n

\n
\n
\"\"<\/a><\/div>\n<\/div>\n

Preempt memory problems by restarting VB6 (or rebooting the PC) once per day<\/h2>\n

While restarting on high memory is a good safety net, it is unpredictable. Your customers may notice a brief interruption if a restart occurs at a busy time.<\/p>\n

Consider instead, a proactive daily restart — to flush the accumulated memory leaks and start your VB6 program afresh. With a clean slate, your application should run reliably for some time before the excessive leaks bog it down again.<\/p>\n

You can configure a daily restart on the Monitor tab as well. Here we have asked AlwaysUp to stop and restart the application every day at 2 AM:<\/p>\n

\"AlwaysUp<\/a><\/div>\n

Note that you can:<\/p>\n

    \n
  • Reboot the entire machine. This may be necessary if you find that restarting the application alone doesn’t clear the problems.<\/li>\n
  • Restart\/reboot only when certain conditions are met. For example, you can skip the restart if the application is busy (i.e. using CPU), or if it hasn’t used much memory yet.<\/li>\n<\/ul>\n

    Whatever works for your situation!<\/p>\n

    Want to restart your Visual Basic program more than once per day? This article<\/a> reviews some alternatives.<\/p>\n

    \nThose two settings should help. Best of luck with your application!<\/p>\n