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| author | Mole Shang <[email protected]> | 2024-02-17 11:55:33 +0800 |
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| committer | Mole Shang <[email protected]> | 2024-02-17 12:22:07 +0800 |
| commit | e8e0a7b4c97064eb5e9415726d7e38aaceccd3fd (patch) | |
| tree | fb42ba5be7a8ae608b968266f62fd71fa889a89d /answers-thread.txt | |
| parent | a6af72924b115c1177d18d9b1eaba56623e4248b (diff) | |
| parent | d85aec2689c4250d0384904bdc11aa618c726bec (diff) | |
| download | xv6-labs-e8e0a7b4c97064eb5e9415726d7e38aaceccd3fd.tar.gz xv6-labs-e8e0a7b4c97064eb5e9415726d7e38aaceccd3fd.tar.bz2 xv6-labs-e8e0a7b4c97064eb5e9415726d7e38aaceccd3fd.zip | |
Merge branch 'thread' into fs
Conflicts:
.gitignore
Makefile
conf/lab.mk
kernel/param.h
Diffstat (limited to 'answers-thread.txt')
| -rw-r--r-- | answers-thread.txt | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/answers-thread.txt b/answers-thread.txt new file mode 100644 index 0000000..80dde35 --- /dev/null +++ b/answers-thread.txt @@ -0,0 +1,10 @@ +1. Why are there missing keys with 2 threads, but not with 1 thread? + With 1 thread, the put and insert are always interleaved. + No changes to hash table happen at the same time. + But with 2 threads, there will be race to access the hash table, + and this leads to the missing keys. + +2. Identify a sequence of events with 2 threads that can lead to a key being missing. + Suppose thread No. 1 is running the insert and so does thread No. 2. + They shall both insert a entry. But because they enter the insert function with the same hash table, + they could only insert one key at most, which causes a key being missing. |