leekeiabstraction commented on code in PR #404:
URL: https://github.com/apache/fluss-rust/pull/404#discussion_r2892809883
##########
crates/fluss/src/client/write/accumulator.rs:
##########
@@ -15,21 +15,142 @@
// specific language governing permissions and limitations
// under the License.
+use crate::client::broadcast;
+use crate::client::write::IdempotenceManager;
use crate::client::write::batch::WriteBatch::{ArrowLog, Kv};
use crate::client::write::batch::{ArrowLogWriteBatch, KvWriteBatch,
WriteBatch};
use crate::client::{LogWriteRecord, Record, ResultHandle, WriteRecord};
use crate::cluster::{BucketLocation, Cluster, ServerNode};
use crate::config::Config;
-use crate::error::Result;
+use crate::error::{Error, Result};
use crate::metadata::{PhysicalTablePath, TableBucket};
+use crate::record::{NO_BATCH_SEQUENCE, NO_WRITER_ID};
use crate::util::current_time_ms;
use crate::{BucketId, PartitionId, TableId};
use dashmap::DashMap;
-use parking_lot::Mutex;
-use parking_lot::RwLock;
+use parking_lot::{Condvar, Mutex, RwLock};
use std::collections::{HashMap, HashSet, VecDeque};
use std::sync::Arc;
-use std::sync::atomic::{AtomicI32, AtomicI64, Ordering};
+use std::sync::atomic::{AtomicBool, AtomicI32, AtomicI64, AtomicUsize,
Ordering};
+use std::time::{Duration, Instant};
+
+/// Byte-counting semaphore that blocks producers when total buffered memory
+/// exceeds the configured limit. Matches Java's `LazyMemorySegmentPool`
behavior.
+///
+/// TODO: Replace `notify_all()` with per-waiter FIFO signaling (Java uses
per-request
+/// Condition objects in a Deque) to avoid thundering herd under high
contention.
+///
+/// TODO: Track actual batch memory usage instead of reserving a fixed
`writer_batch_size`
+/// per batch. This over-counts when batches don't fill completely, reducing
effective
+/// throughput. Requires tighter coupling with batch internals.
Review Comment:
I think there's an undercounting problem as well i.e. if rows are large in
bytes size
##########
crates/fluss/src/client/write/accumulator.rs:
##########
@@ -15,21 +15,142 @@
// specific language governing permissions and limitations
// under the License.
+use crate::client::broadcast;
+use crate::client::write::IdempotenceManager;
use crate::client::write::batch::WriteBatch::{ArrowLog, Kv};
use crate::client::write::batch::{ArrowLogWriteBatch, KvWriteBatch,
WriteBatch};
use crate::client::{LogWriteRecord, Record, ResultHandle, WriteRecord};
use crate::cluster::{BucketLocation, Cluster, ServerNode};
use crate::config::Config;
-use crate::error::Result;
+use crate::error::{Error, Result};
use crate::metadata::{PhysicalTablePath, TableBucket};
+use crate::record::{NO_BATCH_SEQUENCE, NO_WRITER_ID};
use crate::util::current_time_ms;
use crate::{BucketId, PartitionId, TableId};
use dashmap::DashMap;
-use parking_lot::Mutex;
-use parking_lot::RwLock;
+use parking_lot::{Condvar, Mutex, RwLock};
use std::collections::{HashMap, HashSet, VecDeque};
use std::sync::Arc;
-use std::sync::atomic::{AtomicI32, AtomicI64, Ordering};
+use std::sync::atomic::{AtomicBool, AtomicI32, AtomicI64, AtomicUsize,
Ordering};
+use std::time::{Duration, Instant};
+
+/// Byte-counting semaphore that blocks producers when total buffered memory
+/// exceeds the configured limit. Matches Java's `LazyMemorySegmentPool`
behavior.
+///
+/// TODO: Replace `notify_all()` with per-waiter FIFO signaling (Java uses
per-request
+/// Condition objects in a Deque) to avoid thundering herd under high
contention.
+///
+/// TODO: Track actual batch memory usage instead of reserving a fixed
`writer_batch_size`
+/// per batch. This over-counts when batches don't fill completely, reducing
effective
+/// throughput. Requires tighter coupling with batch internals.
+pub(crate) struct MemoryLimiter {
+ state: Mutex<usize>,
+ cond: Condvar,
+ max_memory: usize,
+ wait_timeout: Duration,
+ closed: AtomicBool,
+ waiting_count: AtomicUsize,
+}
+
+impl MemoryLimiter {
+ pub fn new(max_memory: usize, wait_timeout: Duration) -> Self {
+ Self {
+ state: Mutex::new(0),
+ cond: Condvar::new(),
+ max_memory,
+ wait_timeout,
+ closed: AtomicBool::new(false),
+ waiting_count: AtomicUsize::new(0),
+ }
+ }
+
+ /// Try to acquire `size` bytes. Blocks until memory is available,
+ /// the timeout expires, or the limiter is closed.
+ /// Returns a `MemoryPermit` on success.
+ pub fn acquire(self: &Arc<Self>, size: usize) -> Result<MemoryPermit> {
Review Comment:
Given this backpressure mechanism, would a hot bucket cause backpressure
such that writes to other free buckets are slowed down or blocked?
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