[I] `DatagramOutputStream` reallocates and copies its whole buffer on every `write()` [logging-log4j2]

["ppkarwasz (via GitHub)" <gi...@apache.org>]

ppkarwasz opened a new issue, #4333:
URL: https://github.com/apache/logging-log4j2/issues/4333

   `DatagramOutputStream#copy` allocates a new array of exactly the accumulated length and copies the previous contents on every `write()` call. The encoder writes a formatted event in chunks of `Constants.ENCODER_BYTE_BUFFER_SIZE` (8 KiB), so accumulating an event of n bytes before `flush()` sends the datagram costs O(n²): a benchmark writing a single value in 8 KiB chunks takes 0.15 s for 8 MB, 6 s for 64 MB and 99 s for 256 MB, quadrupling each time the payload doubles.
   
   In practice the effect is bounded: `protocol="UDP"` forces `immediateFlush`, so the accumulator is reset after every event, and `DatagramSocket#send` rejects payloads above 65,507 bytes, so a deliverable event needs at most eight copies. Events larger than that already fail at send time. This is therefore a performance and code-quality bug, not a security issue; it originates from a private security report classified as a bug.
   
   Proposal: back the accumulator with a growable buffer (`ByteArrayOutputStream` or a manually doubled array), and reject an accumulated payload above the maximum datagram size in `flush()` with a `StatusLogger` warning instead of letting `send()` fail.
   
   Reported by @August829
   


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Re: [I] `DatagramOutputStream` reallocates and copies its whole buffer on every `write()` [logging-log4j2]

["ramanathan1504 (via GitHub)" <gi...@apache.org>]

ramanathan1504 closed issue #4333: `DatagramOutputStream` reallocates and copies its whole buffer on every `write()`
URL: https://github.com/apache/logging-log4j2/issues/4333


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