elink21 commented on PR #23933:
URL: https://github.com/apache/beam/pull/23933#issuecomment-1307893137

   > It looks like it's not able to get a cache lock? That's a bit concerning 
since that's the bit of the build process getting modified here... Could 
someone please look into that?
   
   Hi @byronellis , it seems like the combination of GCP buckets features along 
with how Gradle Cache works should cover the possible race conditions, I'm 
listing the findings below: 
   * Gradle Cache composes incremental builds based on layers coming from the 
inputs, in case an input change it will generate another entry, but there are 
not deletions or updates for the same key.
   
   * Remote Gradle Cache verifies that the current layer key doesn’t exist in 
the bucket before trying to build and upload.
   
   *  Read-after-write and read-after-delete operations are already strongly 
consistent on GCP buckets.
   
   * Also, read and write are atomic operations when working with buckets. As 
the cache doesn’t perform delete operations or updates to the same key(object), 
the remaining possible race condition is when two workers are trying to push 
the same key if it doesn’t exist at the same time, in this case the last one 
will be effective, but if the key is the same then it shouldn’t be a problem 
since equal inputs generate equal keys, so it doesn’t matter which one is 
uploaded.
   
   * Old cache is only deleted through a lifecycle rule in the bucket. 
   


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