On Sun, 11 Jun 2023 17:26:28 GMT, Doug Simon <dnsi...@openjdk.org> wrote:
>> This PR reduces the amount of code executed during libgraal initialization. >> This not only improves VM startup overall but all fixes a number of JDK test >> failures that are caused by Java code executing "too early". For example, >> `java/util/Locale/CompatWarning.java` can fail if >> `sun.util.locale.provider.LocaleProviderAdapter` is initialized before the >> `CheckWarning` handler is registered. >> >> Instead of serializing `VM.savedProps` via >> `VMSupport.serializeSavedPropertiesToByteArray`, the >> `jdk.vm.ci.services.Services` class now directly reads >> `Arguments::system_properties()` using `Unsafe`. Furthermore, the value of a >> system property is lazily converted to a `String` from a C string pointer. >> >> ## Times >> >> The basic benchmarking below shows that this change brings the time for a >> nop Java app with eager libgraal initialization (2) down to almost the same >> time as lazy libgraal initialization (1). The latter typically means no >> libgraal initialization happens as a top tier JIT compilation is never >> scheduled in such a short running app. >> >> >> public class Nop { >> public static void main(String[] args) {} >> } >> >> >> (1) Baseline (no options): >> >>> for i in (seq 10); java Nop; end >> 0.05 real 0.04 user 0.01 sys >> 0.04 real 0.03 user 0.01 sys >> 0.04 real 0.03 user 0.01 sys >> 0.04 real 0.03 user 0.01 sys >> 0.03 real 0.03 user 0.00 sys >> 0.04 real 0.03 user 0.01 sys >> 0.04 real 0.03 user 0.00 sys >> 0.03 real 0.03 user 0.00 sys >> 0.04 real 0.03 user 0.01 sys >> 0.03 real 0.03 user 0.00 sys >> >> >> (2) Eagerly initialize libgraal (with PR): >> >>> for i in (seq 10); /usr/bin/time java -XX:+EagerJVMCI Nop; end >> 0.06 real 0.04 user 0.01 sys >> 0.05 real 0.03 user 0.01 sys >> 0.05 real 0.03 user 0.01 sys >> 0.05 real 0.03 user 0.01 sys >> 0.05 real 0.03 user 0.01 sys >> 0.05 real 0.03 user 0.01 sys >> 0.05 real 0.03 user 0.01 sys >> 0.05 real 0.03 user 0.01 sys >> 0.05 real 0.03 user 0.01 sys >> 0.05 real 0.03 user 0.01 sys >> >> >> (3) Eagerly initialize libgraal (without PR): >> >>> for i in (seq 10... > > Doug Simon has updated the pull request with a new target base due to a merge > or a rebase. The incremental webrev excludes the unrelated changes brought in > by the merge/rebase. The pull request contains one additional commit since > the last revision: > > copy system properties into libgraal more efficiently src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/services/Services.java line 314: > 312: String key = toJavaString(unsafe, unsafe.getLong(prop + > keyOffset)); > 313: long valueAddress = unsafe.getLong(prop + valueOffset); > 314: if (valueAddress != 0) { Is the lazy value construction really necessary? It seems like it requires quite a bit of extra machinery. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/14291#discussion_r1226038627