Change A2: Use fixed-length byte array rather than ByteArrayOutputStream #10
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Reading out of a `ByteArrayOutputStream` ---------------------------------------- There's no properly supported way to get the ultimate cumulative byte array stored in a `ByteArrayOutputStream` without doing an array copy - that's what `ByteArrayOutputStream.toByteArray()` does, and that means: * While copying, the JVM heap must briefly hold both the old & new byte arrays - roughly speaking, doubling the memory requirements. * Copying the bytes from one array to another takes a little bit of CPU time (obviously this varies: `System.arraycopy()` for 40MB of bytes takes ~2ms on my M1 machine). Writing into a `ByteArrayOutputStream` -------------------------------------- The new `KnownLengthStore` implementation does 1 array copy for a write. The `BaosStore` implementation: * Allocates a new array 'X' with the size of the new incoming data chunk * Copies data into that array 'X' * Copies array 'X' into the instance's cumulative byte array
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Reading out of a
ByteArrayOutputStreamThere's no properly supported way to get the ultimate cumulative byte array stored in a
ByteArrayOutputStreamwithout doing an array copy - that's whatByteArrayOutputStream.toByteArray()does, and that means:System.arraycopy()for 40MB of bytes takes ~2ms on my M1 machine).Writing into a
ByteArrayOutputStreamThe new
KnownLengthStoreimplementation does 1 array copy for a write.The
BaosStoreimplementation:Required RAM: 644 MB