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https://issues.apache.org/jira/browse/ARROW-1795?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16250915#comment-16250915
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ASF GitHub Bot commented on ARROW-1795:
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robertnishihara commented on a change in pull request #1317: ARROW-1795:
[Plasma] Fixes to eviction policy.
URL: https://github.com/apache/arrow/pull/1317#discussion_r150742783
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File path: cpp/src/plasma/eviction_policy.cc
##########
@@ -67,32 +67,24 @@ int64_t EvictionPolicy::choose_objects_to_evict(int64_t
num_bytes_required,
void EvictionPolicy::object_created(const ObjectID& object_id) {
auto entry = store_info_->objects[object_id].get();
cache_.add(object_id, entry->info.data_size + entry->info.metadata_size);
+ int64_t size = entry->info.data_size + entry->info.metadata_size;
+ memory_used_ += size;
}
bool EvictionPolicy::require_space(int64_t size,
std::vector<ObjectID>* objects_to_evict) {
/* Check if there is enough space to create the object. */
int64_t required_space = memory_used_ + size - store_info_->memory_capacity;
- int64_t num_bytes_evicted;
- if (required_space > 0) {
- /* Try to free up at least as much space as we need right now but ideally
Review comment:
Even if `required_space` is 0, we should still try to evict stuff because.
This method is only being called because we need more space, which can happen
even if `required_space` is 0 (due to fragmentation and things like that).
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> [Plasma C++] change evict policy
> --------------------------------
>
> Key: ARROW-1795
> URL: https://issues.apache.org/jira/browse/ARROW-1795
> Project: Apache Arrow
> Issue Type: Improvement
> Components: Plasma (C++)
> Reporter: Lu Qi
> Assignee: Lu Qi
> Priority: Minor
> Labels: pull-request-available
>
> case 1.say, we have total free memory 8 G , we have input 5G data, then comes
> another 6G data,
> if we choose to evict space 6G , it will throw exception saying that
> no object can be free. This is because we didn't count the 3G remaining free
> space .If we count this remaining 3G , we need to ask only 3G,thus
> we can evict the 5G data and we are still alive .
> case 2. another situation is : if we have free memory 10G , we input 1.5G
> data ,then comes another
> 9G data , if we use 10*20% = 2G data to evict ,then we will crash . In this
> situation we need to
> use 9+1.5-10 = 0.5G data to evict
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