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Don't compact with zero input files

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Summary:
We have an issue with internal service trying to run compaction with zero input files:
2014/02/07-02:26:58.386531 7f79117ec700 Compaction start summary: Base version 1420 Base level 3, seek compaction:0, inputs:[ϛ~^Qy^?],[]
2014/02/07-02:26:58.386539 7f79117ec700 Compacted 0@3 + 0@4 files => 0 bytes

There are two issues:
* inputsummary is printing out junk
* it's constantly retrying (since I guess madeProgress is true), so it prints out a lot of data in the LOG file (40GB in one day).

I read through the Level compaction picker and added some failure condition if input[0] is empty. I think PickCompaction() should not return compaction with zero input files with this change. I'm not confident enough to add an assertion though :)

Test Plan: make check

Reviewers: dhruba, haobo, sdong, kailiu

Reviewed By: haobo

CC: leveldb

Differential Revision: https://reviews.facebook.net/D16005
This commit is contained in:
Igor Canadi 2014-03-19 16:01:25 -07:00
parent 1ad0c2f9db
commit e493f2f54e
2 changed files with 7 additions and 4 deletions
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5
db/compaction.cc
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@ -197,6 +197,7 @@ static void FileSizeSummary(unsigned long long sz, char* output, int len) {
static int InputSummary(std::vector<FileMetaData*>& files, char* output,
int len) {
*output = '\0';
int write = 0;
for (unsigned int i = 0; i < files.size(); i++) {
int sz = len - write;
@ -233,9 +234,7 @@ void Compaction::Summary(char* output, int len) {
return;
}
if (inputs_[1].size()) {
write += InputSummary(inputs_[1], output+write, len-write);
}
write += InputSummary(inputs_[1], output+write, len-write);
if (write < 0 || write >= len) {
return;
}

6
db/compaction_picker.cc
View File

@ -178,7 +178,11 @@ bool CompactionPicker::ExpandWhileOverlapping(Compaction* c) {
// If, after the expansion, there are files that are already under
// compaction, then we must drop/cancel this compaction.
int parent_index = -1;
if (FilesInCompaction(c->inputs_[0]) ||
if (c->inputs_[0].empty()) {
Log(options_->info_log,
"ExpandWhileOverlapping() failure because zero input files");
}
if (c->inputs_[0].empty() || FilesInCompaction(c->inputs_[0]) ||
(c->level() != c->output_level() &&
ParentRangeInCompaction(c->input_version_, &smallest, &largest, level,
&parent_index))) {