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Buffer info logs when picking compactions and write them out after re…
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…leasing the mutex

Summary: Now while the background thread is picking compactions, it writes out multiple info_logs, especially for universal compaction, which introduces a chance of waiting log writing in mutex, which is bad. To remove this risk, write all those info logs to a buffer and flush it after releasing the mutex.

Test Plan:
make all check
check the log lines while running some tests that trigger compactions.

Reviewers: haobo, igor, dhruba

Reviewed By: dhruba

CC: i.am.jin.lei, dhruba, yhchiang, leveldb, nkg-

Differential Revision: https://reviews.facebook.net/D16515
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@siying
siying committed Mar 5, 2014
1 parent 4405f3a commit ecb1ffa
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Showing 8 changed files with 227 additions and 120 deletions.
106 changes: 50 additions & 56 deletions db/compaction_picker.cc
View file
Original file line number Diff line number Diff line change
Expand Up @@ -367,7 +367,8 @@ Compaction* CompactionPicker::CompactRange(Version* version, int input_level,
return c;
}

Compaction* LevelCompactionPicker::PickCompaction(Version* version) {
Compaction* LevelCompactionPicker::PickCompaction(Version* version,
LogBuffer* log_buffer) {
Compaction* c = nullptr;
int level = -1;

Expand Down Expand Up @@ -544,40 +545,43 @@ Compaction* LevelCompactionPicker::PickCompactionBySize(Version* version,
// Universal style of compaction. Pick files that are contiguous in
// time-range to compact.
//
Compaction* UniversalCompactionPicker::PickCompaction(Version* version) {
Compaction* UniversalCompactionPicker::PickCompaction(Version* version,
LogBuffer* log_buffer) {
int level = 0;
double score = version->compaction_score_[0];

if ((version->files_[level].size() <
(unsigned int)options_->level0_file_num_compaction_trigger)) {
Log(options_->info_log, "Universal: nothing to do\n");
LogToBuffer(log_buffer, "Universal: nothing to do\n");
return nullptr;
}
Version::FileSummaryStorage tmp;
Log(options_->info_log, "Universal: candidate files(%zu): %s\n",
version->files_[level].size(),
version->LevelFileSummary(&tmp, 0));
LogToBuffer(log_buffer, "Universal: candidate files(%zu): %s\n",
version->files_[level].size(),
version->LevelFileSummary(&tmp, 0));

// Check for size amplification first.
Compaction* c;
if ((c = PickCompactionUniversalSizeAmp(version, score)) != nullptr) {
Log(options_->info_log, "Universal: compacting for size amp\n");
if ((c = PickCompactionUniversalSizeAmp(version, score, log_buffer)) !=
nullptr) {
LogToBuffer(log_buffer, "Universal: compacting for size amp\n");
} else {

// Size amplification is within limits. Try reducing read
// amplification while maintaining file size ratios.
unsigned int ratio = options_->compaction_options_universal.size_ratio;

if ((c = PickCompactionUniversalReadAmp(version, score, ratio, UINT_MAX)) != nullptr) {
Log(options_->info_log, "Universal: compacting for size ratio\n");
if ((c = PickCompactionUniversalReadAmp(version, score, ratio, UINT_MAX,
log_buffer)) != nullptr) {
LogToBuffer(log_buffer, "Universal: compacting for size ratio\n");
} else {
// Size amplification and file size ratios are within configured limits.
// If max read amplification is exceeding configured limits, then force
// compaction without looking at filesize ratios and try to reduce
// the number of files to fewer than level0_file_num_compaction_trigger.
unsigned int num_files = version->files_[level].size() -
options_->level0_file_num_compaction_trigger;
if ((c = PickCompactionUniversalReadAmp(version, score, UINT_MAX, num_files)) != nullptr) {
if ((c = PickCompactionUniversalReadAmp(
version, score, UINT_MAX, num_files, log_buffer)) != nullptr) {
Log(options_->info_log, "Universal: compacting for file num\n");
}
}
Expand Down Expand Up @@ -631,7 +635,7 @@ Compaction* UniversalCompactionPicker::PickCompaction(Version* version) {
//
Compaction* UniversalCompactionPicker::PickCompactionUniversalReadAmp(
Version* version, double score, unsigned int ratio,
unsigned int max_number_of_files_to_compact) {
unsigned int max_number_of_files_to_compact, LogBuffer* log_buffer) {
int level = 0;

unsigned int min_merge_width =
Expand Down Expand Up @@ -666,18 +670,18 @@ Compaction* UniversalCompactionPicker::PickCompactionUniversalReadAmp(
candidate_count = 1;
break;
}
Log(options_->info_log,
"Universal: file %lu[%d] being compacted, skipping",
(unsigned long)f->number, loop);
LogToBuffer(log_buffer,
"Universal: file %lu[%d] being compacted, skipping",
(unsigned long)f->number, loop);
f = nullptr;
}

// This file is not being compacted. Consider it as the
// first candidate to be compacted.
uint64_t candidate_size = f != nullptr? f->file_size : 0;
if (f != nullptr) {
Log(options_->info_log, "Universal: Possible candidate file %lu[%d].",
(unsigned long)f->number, loop);
LogToBuffer(log_buffer, "Universal: Possible candidate file %lu[%d].",
(unsigned long)f->number, loop);
}

// Check if the suceeding files need compaction.
Expand Down Expand Up @@ -727,12 +731,10 @@ Compaction* UniversalCompactionPicker::PickCompactionUniversalReadAmp(
i < loop + candidate_count && i < file_by_time.size(); i++) {
int index = file_by_time[i];
FileMetaData* f = version->files_[level][index];
Log(options_->info_log,
"Universal: Skipping file %lu[%d] with size %lu %d\n",
(unsigned long)f->number,
i,
(unsigned long)f->file_size,
f->being_compacted);
LogToBuffer(log_buffer,
"Universal: Skipping file %lu[%d] with size %lu %d\n",
(unsigned long)f->number, i, (unsigned long)f->file_size,
f->being_compacted);
}
}
}
Expand Down Expand Up @@ -766,10 +768,8 @@ Compaction* UniversalCompactionPicker::PickCompactionUniversalReadAmp(
int index = file_by_time[i];
FileMetaData* f = c->input_version_->files_[level][index];
c->inputs_[0].push_back(f);
Log(options_->info_log, "Universal: Picking file %lu[%d] with size %lu\n",
(unsigned long)f->number,
i,
(unsigned long)f->file_size);
LogToBuffer(log_buffer, "Universal: Picking file %lu[%d] with size %lu\n",
(unsigned long)f->number, i, (unsigned long)f->file_size);
}
return c;
}
Expand All @@ -781,7 +781,7 @@ Compaction* UniversalCompactionPicker::PickCompactionUniversalReadAmp(
// min_merge_width and max_merge_width).
//
Compaction* UniversalCompactionPicker::PickCompactionUniversalSizeAmp(
Version* version, double score) {
Version* version, double score, LogBuffer* log_buffer) {
int level = 0;

// percentage flexibilty while reducing size amplification
Expand All @@ -805,31 +805,27 @@ Compaction* UniversalCompactionPicker::PickCompactionUniversalSizeAmp(
start_index = loop; // Consider this as the first candidate.
break;
}
Log(options_->info_log, "Universal: skipping file %lu[%d] compacted %s",
(unsigned long)f->number,
loop,
" cannot be a candidate to reduce size amp.\n");
LogToBuffer(log_buffer, "Universal: skipping file %lu[%d] compacted %s",
(unsigned long)f->number, loop,
" cannot be a candidate to reduce size amp.\n");
f = nullptr;
}
if (f == nullptr) {
return nullptr; // no candidate files
}

Log(options_->info_log, "Universal: First candidate file %lu[%d] %s",
(unsigned long)f->number,
start_index,
" to reduce size amp.\n");
LogToBuffer(log_buffer, "Universal: First candidate file %lu[%d] %s",
(unsigned long)f->number, start_index, " to reduce size amp.\n");

// keep adding up all the remaining files
for (unsigned int loop = start_index; loop < file_by_time.size() - 1;
loop++) {
int index = file_by_time[loop];
f = version->files_[level][index];
if (f->being_compacted) {
Log(options_->info_log,
"Universal: Possible candidate file %lu[%d] %s.",
(unsigned long)f->number,
loop,
LogToBuffer(
log_buffer, "Universal: Possible candidate file %lu[%d] %s.",
(unsigned long)f->number, loop,
" is already being compacted. No size amp reduction possible.\n");
return nullptr;
}
Expand All @@ -846,18 +842,18 @@ Compaction* UniversalCompactionPicker::PickCompactionUniversalSizeAmp(

// size amplification = percentage of additional size
if (candidate_size * 100 < ratio * earliest_file_size) {
Log(options_->info_log,
"Universal: size amp not needed. newer-files-total-size %lu "
"earliest-file-size %lu",
(unsigned long)candidate_size,
(unsigned long)earliest_file_size);
LogToBuffer(log_buffer,
"Universal: size amp not needed. newer-files-total-size %lu "
"earliest-file-size %lu",
(unsigned long)candidate_size,
(unsigned long)earliest_file_size);
return nullptr;
} else {
Log(options_->info_log,
"Universal: size amp needed. newer-files-total-size %lu "
"earliest-file-size %lu",
(unsigned long)candidate_size,
(unsigned long)earliest_file_size);
LogToBuffer(log_buffer,
"Universal: size amp needed. newer-files-total-size %lu "
"earliest-file-size %lu",
(unsigned long)candidate_size,
(unsigned long)earliest_file_size);
}
assert(start_index >= 0 && start_index < file_by_time.size() - 1);

Expand All @@ -871,11 +867,9 @@ Compaction* UniversalCompactionPicker::PickCompactionUniversalSizeAmp(
int index = file_by_time[loop];
f = c->input_version_->files_[level][index];
c->inputs_[0].push_back(f);
Log(options_->info_log,
"Universal: size amp picking file %lu[%d] with size %lu",
(unsigned long)f->number,
index,
(unsigned long)f->file_size);
LogToBuffer(log_buffer,
"Universal: size amp picking file %lu[%d] with size %lu",
(unsigned long)f->number, index, (unsigned long)f->file_size);
}
return c;
}
Expand Down
16 changes: 11 additions & 5 deletions db/compaction_picker.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -19,6 +19,7 @@

namespace rocksdb {

class LogBuffer;
class Compaction;
class Version;

Expand All @@ -31,7 +32,8 @@ class CompactionPicker {
// Returns nullptr if there is no compaction to be done.
// Otherwise returns a pointer to a heap-allocated object that
// describes the compaction. Caller should delete the result.
virtual Compaction* PickCompaction(Version* version) = 0;
virtual Compaction* PickCompaction(Version* version,
LogBuffer* log_buffer) = 0;

// Return a compaction object for compacting the range [begin,end] in
// the specified level. Returns nullptr if there is nothing in that
Expand Down Expand Up @@ -127,24 +129,28 @@ class UniversalCompactionPicker : public CompactionPicker {
UniversalCompactionPicker(const Options* options,
const InternalKeyComparator* icmp)
: CompactionPicker(options, icmp) {}
virtual Compaction* PickCompaction(Version* version) override;
virtual Compaction* PickCompaction(Version* version,
LogBuffer* log_buffer) override;

private:
// Pick Universal compaction to limit read amplification
Compaction* PickCompactionUniversalReadAmp(Version* version, double score,
unsigned int ratio,
unsigned int num_files);
unsigned int num_files,
LogBuffer* log_buffer);

// Pick Universal compaction to limit space amplification.
Compaction* PickCompactionUniversalSizeAmp(Version* version, double score);
Compaction* PickCompactionUniversalSizeAmp(Version* version, double score,
LogBuffer* log_buffer);
};

class LevelCompactionPicker : public CompactionPicker {
public:
LevelCompactionPicker(const Options* options,
const InternalKeyComparator* icmp)
: CompactionPicker(options, icmp) {}
virtual Compaction* PickCompaction(Version* version) override;
virtual Compaction* PickCompaction(Version* version,
LogBuffer* log_buffer) override;

private:
// For the specfied level, pick a compaction.
Expand Down
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