Files
seaweedfs/seaweed-volume
Chris Lu 3bd218e030 volume: cut idle memory at high volume counts (#10861)
* volume: start a volume's batch write worker on first use

Mounting a volume started a goroutine parked on a 128-slot channel, plus
the 128-entry batch slice it had already allocated. That is around 6.7KB
per volume the server pays whether or not the volume ever takes a write:
7231 bytes per mounted volume, of which 4101 is goroutine stack.

Only a write that asks for fsync ever reaches the worker, and a
remote-tiered or read-only volume never can. Create the channel and its
goroutine on the first such request instead, and let a write arriving
after Destroy fall back to the inline path rather than queue onto a
worker that has gone.

Measured over 20000 mounted volumes: 7231 -> 1269 bytes each.

* volume: update the heartbeat report state in place

Every heartbeat built a second map of what it was about to tell the
master, holding a freshly allocated short information message per volume,
then swapped it in over the old one -- and computed departures through a
third map of the live volume ids. A server holding 2M volumes rebuilt all
three every VolumePulsePeriod for a report that usually says nothing.

Number the heartbeats instead and mark the entry already held with the
pass that found the copy, so a quiet volume costs a map lookup and no
allocation. Departures are the entries a pass did not mark; the live-id
map is now built only when there are some, sized to them.

Measured over 10000 mounted volumes: 436 -> 196 bytes allocated per
volume per heartbeat.

* volume: fill one volume information message per heartbeat, not per volume

The heartbeat built a message for every volume held so it could hash it,
then dropped all but the few it had something to say about. At 2M volumes
that is 2M messages allocated every VolumePulsePeriod to send almost none
of them.

Fill a message the caller supplies instead, and replace it only when the
heartbeat keeps it, so a server with nothing to report fills the same one
all the way through.

Measured over 10000 mounted volumes: 196 -> 4 bytes allocated per volume
per heartbeat, and a heartbeat runs a third faster.

* volume: drop the per-volume trace from the heartbeat's status read

glog.V(4).Infof evaluates its arguments whether or not the verbosity is
on, so every volume boxed its id into a fresh interface slice on every
heartbeat: 759 of the 773 allocations a 1000-volume heartbeat made, for a
line that at this scale would print millions of unreadable rows.

Measured over 1000 mounted volumes: 4776 -> 1792 bytes and 759 -> 14
allocations per heartbeat, which no longer grows with the volume count.

* seaweed-volume: mirror the in-place heartbeat report state

Same change as the Go volume server: number the heartbeats and mark the
entry already held with the pass that found the copy, instead of building
a second map of hashes and swapping it in.

The volume snapshot must leave the reporting state as it found it, so it
keeps asking through changed() while a real heartbeat marks through
record().

* volume: refuse writes to a closed volume instead of dereferencing nil

Close and Destroy leave the needle map and data backend nil, but a caller
that already holds the volume can still reach the write path, where both
are used unguarded: a write racing a volume deletion took the server down.
syncDelete has always checked; syncWrite and the batch worker had not.

Reachable before this series and now also from the inline fallback a
durable write takes when the worker has gone.

* seaweed-volume: guard the report state with one mutex, as Go does

The full-list flag and the generation that answers it have to move
together. Split across separate atomics they cannot: a request landing
between begin's two reads returns full == false with the generation it
just raised, and one landing between commit's read and its clear is
marked answered by a heartbeat that carried no list. Either way the
resend is dropped.

Neither is reachable today -- every caller reaches this through the
store's RwLock, the flag setters under a read lock and the heartbeat
build under a write lock, so they cannot interleave. The type should not
depend on that being true two files away, and Go holds a single mutex
over exactly these fields.

* test: build the servers under test to match the harness's offset size

The mixed Go/Rust suites run both servers against one dataset, so both
have to agree on the offset width. They did not: the harness built Go
with no tags, 4-byte offsets, while the Rust crate defaults to its 5bytes
feature, and the Rust server then refused the .vif the Go server had just
written -- "bytes_offset mismatch: found 4, expected 5".

Build each side to match the offset size the test binary itself was
compiled with, so a plain `go test` and one with -tags 5BytesOffset both
get a matched pair.
2026-08-21 13:04:56 -07:00
..

SeaweedFS Volume Server (Rust)

A drop-in replacement for the SeaweedFS Go volume server, rewritten in Rust. It uses binary-compatible storage formats (.dat, .idx, .vif) and speaks the same HTTP and gRPC protocols, so it works with an unmodified Go master server.

Building

Requires Rust 1.75+ (2021 edition).

cd seaweed-volume
cargo build --release

The binary is produced at target/release/seaweed-volume.

Running

Start a Go master server first, then point the Rust volume server at it:

# Minimal
seaweed-volume --port 8080 --master localhost:9333 --dir /data/vol1 --max 7

# Multiple data directories
seaweed-volume --port 8080 --master localhost:9333 \
  --dir /mnt/ssd1,/mnt/ssd2 --max 100,100 --disk ssd

# With datacenter/rack topology
seaweed-volume --port 8080 --master localhost:9333 --dir /data/vol1 --max 7 \
  --dataCenter dc1 --rack rack1

# With JWT authentication
seaweed-volume --port 8080 --master localhost:9333 --dir /data/vol1 --max 7 \
  --securityFile /etc/seaweedfs/security.toml

# With TLS (configured in security.toml via [https.volume] and [grpc.volume] sections)
seaweed-volume --port 8080 --master localhost:9333 --dir /data/vol1 --max 7 \
  --securityFile /etc/seaweedfs/security.toml

Common flags

Flag Default Description
--port 8080 HTTP listen port
--port.grpc port+10000 gRPC listen port
--master localhost:9333 Comma-separated master server addresses
--dir /tmp Comma-separated data directories
--max 8 Max volumes per directory (comma-separated)
--ip auto-detect Server IP / identifier
--ip.bind same as --ip Bind address
--dataCenter Datacenter name
--rack Rack name
--disk Disk type tag: hdd, ssd, or custom
--index memory Needle map type: memory, leveldb, leveldbMedium, leveldbLarge
--readMode proxy Non-local read mode: local, proxy, redirect
--fileSizeLimitMB 256 Max upload file size
--minFreeSpace 1 (percent) Min free disk space before marking volumes read-only
--securityFile Path to security.toml for JWT keys and TLS certs
--metricsPort 0 (disabled) Prometheus metrics endpoint port
--whiteList Comma-separated IPs with write permission
--preStopSeconds 10 Graceful drain period before shutdown
--compactionMBps 0 (unlimited) Compaction I/O rate limit
--pprof false Enable pprof HTTP handlers

Set RUST_LOG=debug (or trace, info, warn) for log level control. Set SEAWEED_WRITE_QUEUE=1 to enable batched async write processing.

Features

  • Binary compatible -- reads and writes the same .dat/.idx/.vif files as the Go server; seamless migration with no data conversion.
  • HTTP + gRPC -- full implementation of the volume server HTTP API and all gRPC RPCs including streaming operations (copy, tail, incremental copy, vacuum).
  • Master heartbeat -- bidirectional streaming heartbeat with the Go master server; volume and EC shard registration, leader failover, graceful shutdown deregistration.
  • JWT authentication -- signing key configuration via security.toml with token source precedence (query > header > cookie), file_id claims validation, and separate read/write keys.
  • TLS -- HTTPS for the HTTP API and mTLS for gRPC, configured through security.toml.
  • Erasure coding -- Reed-Solomon EC shard management: mount/unmount, read, rebuild, copy, delete, and shard-to-volume reconstruction.
  • S3 remote storage -- FetchAndWriteNeedle reads from any S3-compatible backend (AWS, MinIO, Wasabi, Backblaze, etc.) and writes locally. Supports VolumeTierMoveDatToRemote/FromRemote for tiered storage.
  • Needle map backends -- in-memory HashMap, LevelDB (via rusty-leveldb), or redb (pure Rust disk-backed) needle maps.
  • Image processing -- on-the-fly resize/crop, JPEG EXIF orientation auto-fix, WebP support.
  • Streaming reads -- large files (>1MB) are streamed via spawn_blocking to avoid blocking the async runtime.
  • Auto-compression -- compressible file types (text, JSON, CSS, JS, SVG, etc.) are gzip-compressed on upload.
  • Prometheus metrics -- counters, histograms, and gauges exported at a dedicated metrics port; optional push gateway support.
  • Graceful shutdown -- SIGINT/SIGTERM handling with configurable preStopSeconds drain period.

Testing

Rust unit tests

cd seaweed-volume
cargo test

Go integration tests

The Go test suite can target either the Go or Rust volume server via the VOLUME_SERVER_IMPL environment variable:

# Run all HTTP + gRPC integration tests against the Rust server
VOLUME_SERVER_IMPL=rust go test -v -count=1 -timeout 1200s \
  ./test/volume_server/grpc/... ./test/volume_server/http/...

# Run a single test
VOLUME_SERVER_IMPL=rust go test -v -count=1 -timeout 60s \
  -run "TestName" ./test/volume_server/http/...

# Run S3 remote storage tests
VOLUME_SERVER_IMPL=rust go test -v -count=1 -timeout 180s \
  -run "TestFetchAndWriteNeedle" ./test/volume_server/grpc/...

Load testing

A load test harness is available at test/volume_server/loadtest/. See that directory for usage instructions and scenarios.

Architecture

The server runs three listeners concurrently:

  • HTTP (Axum 0.7) -- admin and public routers for file upload/download, status, and stats endpoints.
  • gRPC (Tonic 0.12) -- all VolumeServer RPCs from the SeaweedFS protobuf definition.
  • Metrics (optional) -- Prometheus scrape endpoint on a separate port.

Key source modules:

Path Description
src/main.rs Entry point, server startup, signal handling
src/config.rs CLI parsing and configuration resolution
src/server/volume_server.rs HTTP router setup and middleware
src/server/handlers.rs HTTP request handlers (read, write, delete, status)
src/server/grpc_server.rs gRPC service implementation
src/server/heartbeat.rs Master heartbeat loop
src/storage/volume.rs Volume read/write/delete logic
src/storage/needle.rs Needle (file entry) serialization
src/storage/store.rs Multi-volume store management
src/security.rs JWT validation and IP whitelist guard
src/remote_storage/ S3 remote storage backend

See DEV_PLAN.md for the full development history and feature checklist.