feat: add default max readers 32000 (#3465)

crates/storage/db/src/implementation/mdbx/mod.rs

@@ -11,11 +11,16 @@ use reth_libmdbx::{
     SyncMode, RO, RW,
 };
 use std::{ops::Deref, path::Path};
+use tx::Tx;
 
 pub mod cursor;
-
 pub mod tx;
-use tx::Tx;
+
+const GIGABYTE: usize = 1024 * 1024 * 1024;
+const TERABYTE: usize = GIGABYTE * 1024;
+
+/// MDBX allows up to 32767 readers (`MDBX_READERS_LIMIT`), but we limit it to slightly below that
+const DEFAULT_MAX_READERS: u64 = 32_000;
 
 /// Environment used when opening a MDBX environment. RO/RW.
 #[derive(Debug)]
@@ -52,9 +57,6 @@ impl<E: EnvironmentKind> Database for Env<E> {
     }
 }
 
-const GIGABYTE: usize = 1024 * 1024 * 1024;
-const TERABYTE: usize = GIGABYTE * 1024;
-
 impl<E: EnvironmentKind> Env<E> {
     /// Opens the database at the specified path with the given `EnvKind`.
     ///
@@ -85,6 +87,8 @@ impl<E: EnvironmentKind> Env<E> {
                     coalesce: true,
                     ..Default::default()
                 })
+                // configure more readers
+                .set_max_readers(DEFAULT_MAX_READERS)
                 .open(path)
                 .map_err(|e| DatabaseError::FailedToOpen(e.into()))?,
         };

crates/storage/db/src/lib.rs

@@ -114,7 +114,7 @@ pub fn init_db<P: AsRef<std::path::Path>>(path: P) -> eyre::Result<DatabaseEnv>
     }
     #[cfg(feature = "mdbx")]
     {
-        let db = Env::<WriteMap>::open(rpath, EnvKind::RW)?;
+        let db = DatabaseEnv::open(rpath, EnvKind::RW)?;
         db.create_tables()?;
         Ok(db)
     }

crates/storage/libmdbx-rs/src/environment.rs

@@ -6,7 +6,6 @@ use crate::{
     Mode, Transaction, TransactionKind,
 };
 use byteorder::{ByteOrder, NativeEndian};
-use libc::c_uint;
 use mem::size_of;
 use std::{
     ffi::CString,
@@ -376,7 +375,7 @@ where
     E: EnvironmentKind,
 {
     flags: EnvironmentFlags,
-    max_readers: Option<c_uint>,
+    max_readers: Option<u64>,
     max_dbs: Option<u64>,
     rp_augment_limit: Option<u64>,
     loose_limit: Option<u64>,
@@ -453,6 +452,15 @@ where
                     }
                 }
 
+                // set max readers if specified
+                if let Some(max_readers) = self.max_readers {
+                    mdbx_result(ffi::mdbx_env_set_option(
+                        env,
+                        ffi::MDBX_opt_max_readers,
+                        max_readers,
+                    ))?;
+                }
+
                 #[cfg(unix)]
                 fn path_to_bytes<P: AsRef<Path>>(path: P) -> Vec<u8> {
                     use std::os::unix::ffi::OsStrExt;
@@ -544,7 +552,7 @@ where
     /// This defines the number of slots in the lock table that is used to track readers in the
     /// the environment. The default is 126. Starting a read-only transaction normally ties a lock
     /// table slot to the [Transaction] object until it or the [Environment] object is destroyed.
-    pub fn set_max_readers(&mut self, max_readers: c_uint) -> &mut Self {
+    pub fn set_max_readers(&mut self, max_readers: u64) -> &mut Self {
         self.max_readers = Some(max_readers);
         self
     }