Michael Knyszek and Austin Clements
29 October 2025
Go 1.25 includes a new experimental garbage collector called Green Tea, available by setting GOEXPERIMENT=greenteagc at build time. Many workloads spend around 10% less time in the garbage collector, but some workloads see a reduction of up to 40%!
It’s production-ready and already in use at Google, so we encourage you to try it out. We know some workloads don’t benefit as much, or even at all, so your feedback is crucial to helping us move forward. Based on the data we have now, we plan to make it the default in Go 1.26.
To report back with any problems, file a new issue.
To report back with any successes, reply to the existing Green Tea issue.
What follows is a blog post based on Michael Knyszek’s GopherCon 2025 talk. We’ll update this blog post with a link to the talk once it’s available online.
Tracing garbage collection
Before we discuss Green Tea let’s get us all on the same page about garbage collection.
Objects and pointers
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