refactor(bindings/java): replace num_cpus with `std::thread::availa…

…ble_parallelism` (#5080)

refactor(bindings/java): replace num_cpus with std available_parallelism

bindings/java/Cargo.toml

@@ -157,7 +157,6 @@ services-yandex-disk = ["opendal/services-yandex-disk"]
 [dependencies]
 anyhow = "1.0.71"
 jni = "0.21.1"
-num_cpus = "1.15.0"
 once_cell = "1.19.0"
 # this crate won't be published, we always use the local version
 opendal = { version = ">=0", path = "../../core", features = [

bindings/java/src/executor.rs

@@ -18,6 +18,8 @@
 use std::cell::RefCell;
 use std::ffi::c_void;
 use std::future::Future;
+use std::num::NonZeroUsize;
+use std::thread::available_parallelism;
 
 use jni::objects::JClass;
 use jni::objects::JObject;
@@ -152,5 +154,10 @@ pub(crate) fn executor_or_default<'a>(
 ///
 /// This function could be only when the lib is loaded.
 unsafe fn default_executor<'a>(env: &mut JNIEnv<'a>) -> Result<&'a Executor> {
-    RUNTIME.get_or_try_init(|| make_tokio_executor(env, num_cpus::get()))
+    RUNTIME.get_or_try_init(|| {
+        make_tokio_executor(
+            env,
+            available_parallelism().map(NonZeroUsize::get).unwrap_or(1),
+        )
+    })
 }