Steve Loughran

I've started work on a fs-api-shim library, with the goal of "apps compile against hadoop 3.2.0 can get access to the 3.3 and 3.4 APIs when available either with transparent...

> perhaps check if the ByteBufferReadable interface is implemented in the stream? The requirement for the `hasCapability("in:readbytebuffer")` to return true postdates the API; there's no way to be confident that...

(i could of course add those probes into the shim class, so at least that access of internals was in one place)

ypu might want to look at WeakReferences...we've been using them recently to implement threadlocal-like storage where GCs will trigger cleanup of instances which aren't being used any more https://github.com/apache/hadoop/blob/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/impl/WeakReferenceThreadMap.java https://github.com/apache/hadoop/blob/trunk/hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/WeakReferenceMap.java...

It is a signature change, but not the return value. The type of the argument to `setInstantiatorStrategy` changed between 2.21 to 2.22; as the package of `InstantiatorStrategy` moved from `org.objenesis.strategy`...

I just want to highlight here that the move to using the client builder apis in the s3a client (HADOOP-13551) was one of the most traumatic regressions of recent years...

note: the deployment seeing this is running in EC2, talking to a local s3 bucket. responses will be fast, if that is a factor

also, I don't see anywhere in my local JDK where the string "/ by zero" is generated; in the JDK it's always "Division By Zero". Where i can find it...

this is weirder than i can imagine. if it was c/c++ i'd say "stack is toast" 1. floating point division returns NaN, not an exception 2. `new ArithmeticException("/ by 0")`...

update / by 0 is the error message from the JVM; but there are no integer division calls in the bytecode of the class