Package org.rocksdb

Class RateLimiter

  • All Implemented Interfaces:
    java.lang.AutoCloseable
    public class RateLimiter
extends RocksObject
    RateLimiter, which is used to control write rate of flush and compaction.
    Since:
    3.10.0

    • Constructor Detail

      • RateLimiter

        public RateLimiter​(long rateBytesPerSecond)
        RateLimiter constructor
        Parameters:
        rateBytesPerSecond - this is the only parameter you want to set most of the time. It controls the total write rate of compaction and flush in bytes per second. Currently, RocksDB does not enforce rate limit for anything other than flush and compaction, e.g. write to WAL.

      • RateLimiter

        public RateLimiter​(long rateBytesPerSecond,
                   long refillPeriodMicros)
        RateLimiter constructor
        Parameters:
        rateBytesPerSecond - this is the only parameter you want to set most of the time. It controls the total write rate of compaction and flush in bytes per second. Currently, RocksDB does not enforce rate limit for anything other than flush and compaction, e.g. write to WAL.
        refillPeriodMicros - this controls how often tokens are refilled. For example, when rate_bytes_per_sec is set to 10MB/s and refill_period_us is set to 100ms, then 1MB is refilled every 100ms internally. Larger value can lead to burstier writes while smaller value introduces more CPU overhead. The default of 100,000ms should work for most cases.

      • RateLimiter

        public RateLimiter​(long rateBytesPerSecond,
                   long refillPeriodMicros,
                   int fairness)
        RateLimiter constructor
        Parameters:
        rateBytesPerSecond - this is the only parameter you want to set most of the time. It controls the total write rate of compaction and flush in bytes per second. Currently, RocksDB does not enforce rate limit for anything other than flush and compaction, e.g. write to WAL.
        refillPeriodMicros - this controls how often tokens are refilled. For example, when rate_bytes_per_sec is set to 10MB/s and refill_period_us is set to 100ms, then 1MB is refilled every 100ms internally. Larger value can lead to burstier writes while smaller value introduces more CPU overhead. The default of 100,000ms should work for most cases.
        fairness - RateLimiter accepts high-pri requests and low-pri requests. A low-pri request is usually blocked in favor of hi-pri request. Currently, RocksDB assigns low-pri to request from compaction and high-pri to request from flush. Low-pri requests can get blocked if flush requests come in continuously. This fairness parameter grants low-pri requests permission by fairness chance even though high-pri requests exist to avoid starvation. You should be good by leaving it at default 10.

      • RateLimiter

        public RateLimiter​(long rateBytesPerSecond,
                   long refillPeriodMicros,
                   int fairness,
                   RateLimiterMode rateLimiterMode)
        RateLimiter constructor
        Parameters:
        rateBytesPerSecond - this is the only parameter you want to set most of the time. It controls the total write rate of compaction and flush in bytes per second. Currently, RocksDB does not enforce rate limit for anything other than flush and compaction, e.g. write to WAL.
        refillPeriodMicros - this controls how often tokens are refilled. For example, when rate_bytes_per_sec is set to 10MB/s and refill_period_us is set to 100ms, then 1MB is refilled every 100ms internally. Larger value can lead to burstier writes while smaller value introduces more CPU overhead. The default of 100,000ms should work for most cases.
        fairness - RateLimiter accepts high-pri requests and low-pri requests. A low-pri request is usually blocked in favor of hi-pri request. Currently, RocksDB assigns low-pri to request from compaction and high-pri to request from flush. Low-pri requests can get blocked if flush requests come in continuously. This fairness parameter grants low-pri requests permission by fairness chance even though high-pri requests exist to avoid starvation. You should be good by leaving it at default 10.
        rateLimiterMode - indicates which types of operations count against the limit.

      • RateLimiter

        public RateLimiter​(long rateBytesPerSecond,
                   long refillPeriodMicros,
                   int fairness,
                   RateLimiterMode rateLimiterMode,
                   boolean autoTune)
        RateLimiter constructor
        Parameters:
        rateBytesPerSecond - this is the only parameter you want to set most of the time. It controls the total write rate of compaction and flush in bytes per second. Currently, RocksDB does not enforce rate limit for anything other than flush and compaction, e.g. write to WAL.
        refillPeriodMicros - this controls how often tokens are refilled. For example, when rate_bytes_per_sec is set to 10MB/s and refill_period_us is set to 100ms, then 1MB is refilled every 100ms internally. Larger value can lead to burstier writes while smaller value introduces more CPU overhead. The default of 100,000ms should work for most cases.
        fairness - RateLimiter accepts high-pri requests and low-pri requests. A low-pri request is usually blocked in favor of hi-pri request. Currently, RocksDB assigns low-pri to request from compaction and high-pri to request from flush. Low-pri requests can get blocked if flush requests come in continuously. This fairness parameter grants low-pri requests permission by fairness chance even though high-pri requests exist to avoid starvation. You should be good by leaving it at default 10.
        rateLimiterMode - indicates which types of operations count against the limit.
        autoTune - Enables dynamic adjustment of rate limit within the range [rate_bytes_per_sec / 20, rate_bytes_per_sec], according to the recent demand for background I/O.

    • Method Detail

      • setBytesPerSecond

        public void setBytesPerSecond​(long bytesPerSecond)

        This API allows user to dynamically change rate limiter's bytes per second. REQUIRED: bytes_per_second > 0

        Parameters:
        bytesPerSecond - bytes per second.

      • getBytesPerSecond

        public long getBytesPerSecond()
        Returns the bytes per second.
        Returns:
        bytes per second.

      • request

        public void request​(long bytes)

        Request for token to write bytes. If this request can not be satisfied, the call is blocked. Caller is responsible to make sure bytes < GetSingleBurstBytes().

        Parameters:
        bytes - requested bytes.

      • getSingleBurstBytes

        public long getSingleBurstBytes()

        Max bytes can be granted in a single burst.

        Returns:
        max bytes can be granted in a single burst.

      • getTotalBytesThrough

        public long getTotalBytesThrough()

        Total bytes that go through rate limiter.

        Returns:
        total bytes that go through rate limiter.

      • getTotalRequests

        public long getTotalRequests()

        Total # of requests that go through rate limiter.

        Returns:
        total # of requests that go through rate limiter.