HighFile-scopeJava Plug & play

Handle asynchronous operation failures

Attach exceptionally/handle to CompletableFuture chains; never assume success.

Why this matters

Ensures failures are observed and mapped to consistent outcomes.

Side-by-side examples engineers can pattern-match during review.

Avoid

CompletableFuture<String> f = fetch(); return f.join();

Prefer

return fetch()
  .thenApply(this::ok)
  .exceptionally(e -> error("fetch failed"));

Bad

future.thenApply(...); // no error path

Good

future.handle((v,e) -> e==null?ok(v):error())

From the same buckets as this rule.

Critical
Avoid Blocking Calls to Async Methods
Blocking async methods with `.Result` or `.Wait()` can cause deadlocks and prevent efficient asynchronous execution. Use `await` instead for proper async behavior.
concurrency-safetyperformance-efficiency
Critical
Do Not Call `wait()` When Holding Multiple Locks
Ensure that `wait()` is not called while holding multiple locks to prevent deadlocks.
concurrency-safety
High
Avoid Using Mutable Global Variables
Identify global variables that are mutable (e.g., lists, dictionaries). Global mutable state can cause unpredictable behavior. Recommend using local variables or encapsulating state in a class.
concurrency-safetymaintainability+1