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fix: prevent memory exhaustion on large files (#25) #36

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4409aad
fix: prevent memory exhaustion on large files (#25)
vyagh Dec 25, 2025
ac3b7b7
fix: address review feedback - add stream cleanup and fix error message
vyagh Dec 25, 2025
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204 changes: 130 additions & 74 deletions packages/core/src/tools/read-data-file.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@

import path from 'node:path';
import fs from 'node:fs';
import * as readline from 'node:readline';
import { makeRelative, shortenPath } from '../utils/paths.js';
import type { ToolInvocation, ToolLocation, ToolResult } from './tools.js';
import { BaseDeclarativeTool, BaseToolInvocation, Kind } from './tools.js';
Expand All @@ -14,6 +15,9 @@ import type { Config } from '../config/config.js';
import { ToolErrorType } from './tool-error.js';
import { generateWorkspacePathError } from './workspace-error-helper.js';

const MAX_JSON_FILE_SIZE_MB = 100;
const MAX_JSON_FILE_SIZE_BYTES = MAX_JSON_FILE_SIZE_MB * 1024 * 1024;

/**
* Parameters for the ReadDataFile tool
*/
Expand Down Expand Up @@ -67,11 +71,73 @@ class ReadDataFileToolInvocation extends BaseToolInvocation<
}

/**
* Parse CSV file into structured data with comprehensive analysis
* Simple CSV line parser (handles basic cases including quoted fields)
*/
private async parseCSV(content: string): Promise<ParsedDataResult> {
const lines = content.trim().split('\n');
if (lines.length === 0) {
private parseCSVLine(line: string): Array<string> {
const result: Array<string> = [];
let current = '';
let inQuotes = false;

for (let i = 0; i < line.length; i++) {
const char = line[i];
if (char === '"') {
inQuotes = !inQuotes;
} else if (char === ',' && !inQuotes) {
result.push(current.trim());
current = '';
} else {
current += char;
}
}
result.push(current.trim());
return result;
}

/**
* Parse CSV file using streaming to avoid memory exhaustion on large files
*/
private async parseCSVStream(filePath: string): Promise<ParsedDataResult> {
const displayMaxRows = this.params.max_rows || 100;
const sampleData: Array<Record<string, string>> = [];
let headers: Array<string> = [];
let totalRows = 0;
let isFirstLine = true;

const fileStream = fs.createReadStream(filePath, { encoding: 'utf-8' });
const rl = readline.createInterface({
input: fileStream,
crlfDelay: Infinity,
});

try {
for await (const line of rl) {
const trimmedLine = line.trim();
if (!trimmedLine) continue;

if (isFirstLine) {
headers = this.parseCSVLine(trimmedLine);
isFirstLine = false;
continue;
}

totalRows++;

// Only store rows up to displayMaxRows for the sample
if (sampleData.length < displayMaxRows) {
const values = this.parseCSVLine(trimmedLine);
const row: Record<string, string> = {};
headers.forEach((header, index) => {
row[header] = values[index] || '';
});
sampleData.push(row);
}
}
} finally {
rl.close();
fileStream.destroy();
}

if (headers.length === 0) {
return {
fileType: 'CSV',
data: [],
Expand All @@ -80,54 +146,14 @@ class ReadDataFileToolInvocation extends BaseToolInvocation<
};
}

// Simple CSV parser (handles basic cases, not production-grade)
const parseCSVLine = (line: string): string[] => {
const result: string[] = [];
let current = '';
let inQuotes = false;

for (let i = 0; i < line.length; i++) {
const char = line[i];
if (char === '"') {
inQuotes = !inQuotes;
} else if (char === ',' && !inQuotes) {
result.push(current.trim());
current = '';
} else {
current += char;
}
}
result.push(current.trim());
return result;
};

const headers = parseCSVLine(lines[0]);
const totalRows = lines.length - 1;

// Parse rows, limit display if max_rows is set
const allDataRows = lines.slice(1);
const displayMaxRows = this.params.max_rows || 100; // Default to 100 for display

// Parse data rows
const allData = allDataRows.map((line) => {
const values = parseCSVLine(line);
const row: Record<string, string> = {};
headers.forEach((header, index) => {
row[header] = values[index] || '';
});
return row;
});

// Data to display (limited if max_rows is set)
const displayData = displayMaxRows ? allData.slice(0, displayMaxRows) : allData;

const summaryText = displayMaxRows && totalRows > displayMaxRows
? `CSV file with ${headers.length} columns and ${totalRows} rows (showing first ${displayMaxRows} rows)`
: `CSV file with ${headers.length} columns and ${totalRows} rows`;
const summaryText =
totalRows > displayMaxRows
? `CSV file with ${headers.length} columns and ${totalRows} rows (showing first ${displayMaxRows} rows)`
: `CSV file with ${headers.length} columns and ${totalRows} rows`;

return {
fileType: 'CSV',
data: displayData,
data: sampleData,
summary: summaryText,
rowCount: totalRows,
columnCount: headers.length,
Expand Down Expand Up @@ -176,18 +202,36 @@ class ReadDataFileToolInvocation extends BaseToolInvocation<
}

/**
* Parse TXT file (treat as plain text with line-by-line analysis)
* Parse TXT file using streaming to avoid memory exhaustion on large files
*/
private async parseTXT(content: string): Promise<ParsedDataResult> {
const lines = content.split('\n');
private async parseTXTStream(filePath: string): Promise<ParsedDataResult> {
const maxRows = this.params.max_rows || 100;
const limitedLines = lines.slice(0, maxRows);
const sampleLines: Array<string> = [];
let totalLines = 0;

const fileStream = fs.createReadStream(filePath, { encoding: 'utf-8' });
const rl = readline.createInterface({
input: fileStream,
crlfDelay: Infinity,
});

try {
for await (const line of rl) {
totalLines++;
if (sampleLines.length < maxRows) {
sampleLines.push(line);
}
}
} finally {
rl.close();
fileStream.destroy();
}

return {
fileType: 'TXT',
data: limitedLines,
summary: `Text file with ${lines.length} lines (showing first ${limitedLines.length} lines)`,
rowCount: lines.length,
data: sampleLines,
summary: `Text file with ${totalLines} lines (showing first ${sampleLines.length} lines)`,
rowCount: totalLines,
};
}

Expand All @@ -198,10 +242,10 @@ class ReadDataFileToolInvocation extends BaseToolInvocation<
try {
// Dynamic import to handle optional dependency - use default export
const { default: XLSX } = await import('xlsx');

const workbook = XLSX.readFile(filePath);
const sheetNames = workbook.SheetNames;

if (sheetNames.length === 0) {
return {
fileType: 'XLSX',
Expand All @@ -212,27 +256,27 @@ class ReadDataFileToolInvocation extends BaseToolInvocation<
}

const maxRows = this.params.max_rows || 100;

// Parse all sheets and collect their data
const allSheetsData: Record<string, unknown[]> = {};
let totalRows = 0;
let firstSheetColumns: string[] = [];

for (const sheetName of sheetNames) {
const worksheet = workbook.Sheets[sheetName];

// Convert to JSON with proper options
const jsonData = XLSX.utils.sheet_to_json(worksheet, {
raw: false, // Format numbers and dates
defval: '', // Default value for empty cells
});

allSheetsData[sheetName] = jsonData;
totalRows += jsonData.length;

// Get column names from first sheet's first row
if (sheetName === sheetNames[0] && jsonData.length > 0 &&
typeof jsonData[0] === 'object' && jsonData[0] !== null) {
if (sheetName === sheetNames[0] && jsonData.length > 0 &&
typeof jsonData[0] === 'object' && jsonData[0] !== null) {
firstSheetColumns = Object.keys(jsonData[0] as Record<string, unknown>);
}
}
Expand All @@ -243,7 +287,7 @@ class ReadDataFileToolInvocation extends BaseToolInvocation<
const limitedData = firstSheetData.slice(0, maxRows);

// Create a summary of all sheets
const sheetsSummary = sheetNames.map(name =>
const sheetsSummary = sheetNames.map(name =>
`"${name}" (${allSheetsData[name]?.length || 0} rows)`
).join(', ');

Expand All @@ -268,7 +312,7 @@ class ReadDataFileToolInvocation extends BaseToolInvocation<
};
} catch (error) {
if ((error as NodeJS.ErrnoException).code === 'MODULE_NOT_FOUND' ||
(error as Error).message?.includes('Cannot find module')) {
(error as Error).message?.includes('Cannot find module')) {
return {
fileType: 'XLSX',
data: null,
Expand All @@ -289,10 +333,10 @@ class ReadDataFileToolInvocation extends BaseToolInvocation<
try {
// Dynamic import to handle optional dependency - use default export
const { default: mammoth } = await import('mammoth');

const result = await mammoth.extractRawText({ path: filePath });
const text = result.value;

// Split into paragraphs
const paragraphs = text
.split('\n')
Expand All @@ -310,7 +354,7 @@ class ReadDataFileToolInvocation extends BaseToolInvocation<
};
} catch (error) {
if ((error as NodeJS.ErrnoException).code === 'MODULE_NOT_FOUND' ||
(error as Error).message?.includes('Cannot find module')) {
(error as Error).message?.includes('Cannot find module')) {
return {
fileType: 'DOCX',
data: null,
Expand Down Expand Up @@ -362,18 +406,30 @@ class ReadDataFileToolInvocation extends BaseToolInvocation<
// Parse based on file type
switch (ext) {
case '.csv': {
const content = await fs.promises.readFile(filePath, 'utf-8');
result = await this.parseCSV(content);
// Use streaming parser to avoid memory exhaustion on large files
result = await this.parseCSVStream(filePath);
break;
}
case '.json': {
// JSON cannot be streamed easily, so enforce a file size limit
if (stats.size > MAX_JSON_FILE_SIZE_BYTES) {
const fileSizeMB = (stats.size / (1024 * 1024)).toFixed(2);
return {
llmContent: `JSON file is too large (${fileSizeMB} MB). Maximum supported size for JSON files is ${MAX_JSON_FILE_SIZE_MB} MB. For large JSON files, use Python with a streaming JSON parser to process the data in chunks.`,
returnDisplay: `JSON file too large (${fileSizeMB} MB, max ${MAX_JSON_FILE_SIZE_MB} MB)`,
error: {
message: `JSON file size (${fileSizeMB} MB) exceeds ${MAX_JSON_FILE_SIZE_MB} MB limit`,
type: ToolErrorType.FILE_TOO_LARGE,
},
};
}
const content = await fs.promises.readFile(filePath, 'utf-8');
result = await this.parseJSON(content);
break;
}
case '.txt': {
const content = await fs.promises.readFile(filePath, 'utf-8');
result = await this.parseTXT(content);
// Use streaming parser to avoid memory exhaustion on large files
result = await this.parseTXTStream(filePath);
break;
}
case '.xlsx':
Expand Down