On Fri, 22 Apr 2022 02:13:14 GMT, David Schlosnagle <d...@openjdk.java.net> wrote:
>> Profiling the TLS handshakes using SSLHandshake benchmark shows that a large >> portion of time is spent in HandshakeContext initialization, specifically in >> DisabledAlgorithmConstraints class. >> >> There are only a few instances of that class, and they are immutable. >> Caching the results should be a low-risk operation. >> >> The cache is implemented as a softly reachable ConcurrentHashMap; this way >> it can be removed from memory after a period of inactivity. Under normal >> circumstances the cache holds no more than 100 algorithms. > > src/java.base/share/classes/sun/security/util/DisabledAlgorithmConstraints.java > line 969: > >> 967: result = checkAlgorithm(disabledAlgorithms, algorithm, >> decomposer); >> 968: cache.put(algorithm, result); >> 969: return result; > > Would it be worth using `cache.computeIfAbsent` or do you want to avoid > lambda allocation overhead and potentially blocking concurrent handshakes on > writer thread? > > Suggestion: > > return cache.computeIfAbsent(algorithm, algo -> > checkAlgorithm(disabledAlgorithms, algo, decomposer)); I generally prefer using `get` over `computeIfAbsent` when optimizing for performance. While `computeIfAbsent` is more concise, it's also much slower than `get` when the entry is already present. ------------- PR: https://git.openjdk.java.net/jdk/pull/8349
