Chunked getSectionsText() to lower peak memory#828
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getSectionsText() ran the formatted content stream through a single preg_split() into an array of every line, then kept only the handful needed for text positioning. A vector-graphics-heavy page can format to hundreds of thousands of lines while yielding almost no text, so that array was the peak of the whole text-extraction phase. Split the formatted stream in, line-aligned 1 MB chunks instead. Each chunk is then preg_split(), filtered and then discarded. Where the source stream is smaller than 1 MB, there is no change in behaviour. Output is byte-for-byte identical, and there is virtually no throughput cost. Measured peak memory (parseFile + getText on the whole file) vs master, on a graphics heavy document: samples/bugs/Issue356.pdf 79.4 MB -> 59.2 MB (-25%) Other documents are unchanged (PullRequest457.pdf 146.9 MB, DocumentWithLotsOfObjects.pdf 99.1 MB, Issue391.pdf 10.4 MB).
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Part 2 of #824
getSectionsText() ran the formatted content stream through a single preg_split() into an array of every line, then kept only the handful needed for text positioning. A vector-graphics-heavy page can format to hundreds of thousands of lines while yielding almost no text, so that array was the peak of the whole text-extraction phase.
Split the formatted stream in, line-aligned 1 MB chunks instead. Each chunk is then preg_split(), filtered and then discarded. Where the source stream is smaller than 1 MB, there is no change in behaviour.
Output is byte-for-byte identical, and there is virtually no throughput cost.
Measured peak memory (parseFile + getText on the whole file) vs master, on a graphics heavy document:
samples/bugs/Issue356.pdf 79.4 MB -> 59.2 MB (-25%)
Other documents are unchanged (PullRequest457.pdf 146.9 MB, DocumentWithLotsOfObjects.pdf 99.1 MB, Issue391.pdf 10.4 MB).