shared hash seed in process

common/src/hash.rs

@@ -54,8 +54,9 @@ impl HashSecret {
     pub fn new(seed: u32) -> Self {
         let mut buf = [0u8; 16];
         lcg_urandom(seed, &mut buf);
-        let k0 = u64::from_le_bytes(buf[..8].try_into().unwrap());
-        let k1 = u64::from_le_bytes(buf[8..].try_into().unwrap());
+        let (left, right) = buf.split_at(8);
+        let k0 = u64::from_le_bytes(left.try_into().unwrap());
+        let k1 = u64::from_le_bytes(right.try_into().unwrap());
         Self { k0, k1 }
     }
 }

vm/src/vm/mod.rs

@@ -88,6 +88,12 @@ pub struct PyGlobalState {
     pub codec_registry: CodecsRegistry,
 }
 
+pub fn process_hash_secret_seed() -> u32 {
+    use once_cell::sync::OnceCell;
+    static SEED: OnceCell<u32> = OnceCell::new();
+    *SEED.get_or_init(rand::random)
+}
+
 impl VirtualMachine {
     /// Create a new `VirtualMachine` structure.
     fn new(settings: Settings, ctx: PyRc<Context>) -> VirtualMachine {
@@ -120,10 +126,11 @@ impl VirtualMachine {
 
         let module_inits = stdlib::get_module_inits();
 
-        let hash_secret = match settings.hash_seed {
-            Some(seed) => HashSecret::new(seed),
-            None => rand::random(),
+        let seed = match settings.hash_seed {
+            Some(seed) => seed,
+            None => process_hash_secret_seed(),
         };
+        let hash_secret = HashSecret::new(seed);
 
         let codec_registry = CodecsRegistry::new(&ctx);