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fix(blob): prevent blob eviction when used from cache #68

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Merged
jourdain merged 3 commits into from
Aug 31, 2026
Merged

fix(blob): prevent blob eviction when used from cache #68

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8fff3e2
fix(blob): prevent blob eviction when used from cache
jourdain Aug 28, 2026
e53a6c2
fix(blob): prevent blob eviction when cache is smaller than current v…
jourdain Aug 31, 2026
ce3ae27
docs(blob): expend comment to be more explicit
jourdain Aug 31, 2026
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22 changes: 21 additions & 1 deletion src/remoteSession.js
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Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,7 @@ export class RemoteSession {
this.renderWindowSizes = {};
this.boundRenderWindows = new Set();
this.renderWindowIdsWithRunningEventLoops = new Set();
this.currentBlobs = {}

// renderWindowId -> { canvas, target } where `canvas` is the user-provided
// element and `target` is the string handed to native.bindRenderWindow
Expand Down Expand Up @@ -164,6 +165,12 @@ export class RemoteSession {
freeMemory(cacheSize = 0) {
const memArrays = this.#native.getTotalBlobMemoryUsage();
const threshold = Number(cacheSize);
const usedBlobs = new Set();
Object.values(this.currentBlobs).forEach((hashes) => {
for (let i = 0; i < hashes.length; i++) {
usedBlobs.add(hashes[i]);
}
});

if (memArrays > threshold) {
// Need to remove old blobs
Expand All @@ -182,10 +189,14 @@ export class RemoteSession {
});

// Remove blobs starting by the old ones
while (this.#native.getTotalBlobMemoryUsage() > threshold) {
while (this.#native.getTotalBlobMemoryUsage() > threshold && mtimeToFree < this.currentMTime) {
const hashesToDelete = tsMap[mtimeToFree];
if (hashesToDelete) {
for (let i = 0; i < hashesToDelete.length; i++) {
if (usedBlobs.has(hashesToDelete[i])) {
// do not remove any blob that is currently used
continue;
}
this.#native.unRegisterBlob(hashesToDelete[i]);
delete this.hashesMTime[hashesToDelete[i]];
}
Expand Down Expand Up @@ -320,9 +331,18 @@ export class RemoteSession {
serverStatus.hashes.forEach((hash) => {
if (!this.hashesMTime[hash]) {
hashesToFetch.push(hash);
} else {
// tag existing blob with current mtime so they don't
// get removed at gc for being used from the cache from
// a long time ago.
this.hashesMTime[hash] = this.currentMTime;
}
});

// track hashes needed in current rendering to prevent
// blob eviction
this.currentBlobs[vtkId] = serverStatus.hashes;

this.progressState = {
active: !!(statesToFetch.length + hashesToFetch.length),
state: { current: 0, total: statesToFetch.length },
Expand Down