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decrease max bytes read from hdfs #1633

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Merged
merged 1 commit into from
Feb 9, 2022
Merged

decrease max bytes read from hdfs #1633

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13 changes: 8 additions & 5 deletions tensorflow_io/core/filesystems/hdfs/hadoop_filesystem.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -313,10 +313,11 @@ int64_t Read(const TF_RandomAccessFile* file, uint64_t offset, size_t n,
// concurrent readers.
absl::MutexLock l(&hdfs_file->mu);
auto handle = hdfs_file->handle;
// Max read length is INT_MAX-2, for hdfsPread function take a parameter
// of int32. -2 offset can avoid JVM OutOfMemoryError.
// Max read length is INT_MAX-2.
// Actual max array size in java depends on JVM's implentation
// So we choose INT_MAX-8, which is the maximum "safe" number.
size_t read_n =
(std::min)(n, static_cast<size_t>(std::numeric_limits<int>::max() - 2));
(std::min)(n, static_cast<size_t>(std::numeric_limits<int>::max() - 8));
int64_t r = libhdfs->hdfsPread(fs, handle, static_cast<tOffset>(offset),
dst, static_cast<tSize>(read_n));
if (r > 0) {
Expand Down Expand Up @@ -389,9 +390,11 @@ void Append(const TF_WritableFile* file, const char* buffer, size_t n,

size_t cur_pos = 0, write_len = 0;
bool retry = false;
// max() - 2 can avoid OutOfMemoryError in JVM .

// Actual max array size in java depends on JVM's implentation
// So we choose INT_MAX-8, which is the maximum "safe" number.
static const size_t max_len_once =
static_cast<size_t>(std::numeric_limits<tSize>::max() - 2);
static_cast<size_t>(std::numeric_limits<tSize>::max() - 8);
while (cur_pos < n) {
write_len = (std::min)(n - cur_pos, max_len_once);
tSize w = libhdfs->hdfsWrite(fs, handle, buffer + cur_pos,
Expand Down